Author Archives: mywp

Surface modification of titanium alloy by micro-arc oxidation

Posted on by

Titanium alloys are widely used in aerospace, chemical industry and biomedical fields, but their low hardness, poor anti-wear and anti-friction function restrict their use. Therefore, the use of surface modification skills to improve the appearance function of titanium alloys has attracted much attention. The most commonly used method is chemical treatment or chemical oxidation to improve the contact force between the matrix and the coating and the corrosion resistance of the surface. However, the oxide film obtained by chemical oxidation is thin and has poor corrosion resistance and durability. The oxide film on the surface of titanium alloy makes it difficult to realize electroless plating and electroplating on titanium. In contrast, micro-arc oxidation is widely considered as the most promising method for surface treatment of titanium alloys.

                     

Micro-arc oxidation is a process of in-situ growth of ceramic oxide film in electrolyte solution (usually weak alkaline solution) by applying high voltage (DC, AC or pulse) on the surface of data. This process is the result of synergistic effect of physical discharge, electrochemical oxidation and plasma oxidation. This skill is developed on the basis of general anodic oxidation skills. Further improvement of voltage will lead to the appearance of spark discharge in the anode when the voltage exceeds Faraday area and reaches the breakdown voltage of the oxide film. The ceramic oxide film is formed on the surface of the data, which makes the plasma oxide film both high-functioning and strong. The contact force between the anodic oxide film and the matrix was maintained. These characteristics make it a hot topic in the field of appearance engineering skills. Using micro-arc oxidation technology, Harbin University of Technology of China added cobalt acetate into the electrolyte, thus forming a heat shock resistant ceramic film on TC4 alloy. The connection between the film and the substrate can be higher than 10 MPa. The alloy remains stable under 40 cycles of thermal sensation, indicating that the TC4 alloy treated by micro-arc oxidation has excellent properties. Heat shock resistance.

In recent years, micro-arc oxidation (MAO) coatings formed in electrolytes containing calcium and phosphorus have attracted researchers’interest in bone transplantation due to their high wear resistance, corrosion resistance and biocompatibility. In Korea, nanocrystalline hydrogen-based apatite ceramic coatings were formed on the surface of pure titanium by micro-arc oxidation. The crystallinity and biocompatibility of the nanocrystalline apatite ceramics in the coatings are very high, showing the potential of application in plastic surgery and dental repair skills. The bio-active thin films containing calcium and phosphorus were prepared by micro-arc oxidation at Xi’an Jiaotong University, China. The results show that the thin films are composed of anatase titanium dioxide and rutile titanium dioxide, which are in the form of fine inner layer and porous outer layer; the ratio of calcium and phosphorus atoms in the film increases gradually from inside to outside; and the film can be transformed into a bio-active thin film containing calcium and phosphorus after hydrothermal treatment. Bioactive Titanium Dioxide Layer of Hydrogen-based Apatite. The rutile film has common electrical and mechanical functions.

Because of its excellent physical function and biocompatibility, beta-Ti is considered as the next generation of plastic surgery and dental metal. In order to improve the bone composition of beta-Ti and human bone arrangement, micro-arc oxidation can be used to improve the biological activity of beta-Ti. The titanium dioxide ceramic film was prepared by micro-arc oxidation on beta-Ti alloy in Taiwan, China. The experiment was carried out in vitro and implanted into the thigh tip of Japanese mice. The results show that the titanium dioxide film is formed, which has a strong connection with the base and shows a better bone formation ability than pure titanium. It is more suitable for medical implantation correction.

Market Situation of Titanium Civil Health Products

Posted on by

1. Current market situation

At present, iron, aluminium and stainless steel are widely used in tableware and cooking utensils at home and abroad, which will produce some unhealthy factors to human body more or less.

(1) Iron pot: When iron comes to vegetables, it is trivalent iron. Human body can not absorb it. Human body can absorb only bivalent iron.

(2) Aluminum pot: It is unsafe to dissolve aluminium under high temperature acid and alkali conditions and cause aluminium poisoning. The International Health Organization explicitly prohibits the use of aluminium pots in contact with food containing salts.

(3) Non-stick pots: Most of them use Teflon paint, which the US government accuses of being carcinogenic. Teflon releases more than a dozen harmful gases at high temperatures, leading to the death of some respiratory-sensitive animals. But the toxic effects of these gases on the human body have not yet been determined.

(4) Enamel tableware: The enamel coated on the outer layer of enamel products is actually a layer of enamel, containing aluminum silicate and other substances. Because of the collision and friction of stir-frying, it is easy to cause damage, so that materials such as aluminium silicate will be transferred to food.

Pottery pot and casserole: There are two main potential hazards: one is the enamel of earthen casserole, the other is “pseudo purple sand”. “Pseudo purple sand” is prepared by adding iron red powder, manganese dioxide and other chemical pigments, and is made by adding chemical agents, instead of real purple sand.

2. Advantages of Titanium Health Products

The advantage of titanium health products is that there is a strong titanium oxide film on the surface of titanium metal, and its chemical properties are extremely stable, even the “aqua regia” in acid can not help it. Titanium pot does not react with food materials in cooking. Therefore, the pure titanium pot is the only metal pot that can be used to fry traditional Chinese medicine. In the United States and Japan, people call titanium pot a delicious pot, and the original taste of the sauce is a healthy element.

Titanium pot has excellent thermal function: it can cook green delicacies at low temperature, fast and low fat, and retain the nutrients and taste of the ingredients to the greatest extent. High nutritional green food is a healthy element.

The advantages of titanium tableware and cooking utensils are shown in the following aspects:

(1) Strong corrosion resistance: It is more resistant to corrosion than stainless steel. Even the most corrosive “aqua regia” (mixture of concentrated sulphuric acid and concentrated nitric acid) has no rust. Long-term cooking and storage of acidic and alkaline food will not produce metal odor, and it can also be used to cook traditional Chinese medicine. Other metal pots can’t do that.

High hardness: much higher than stainless steel hardness, wear-resistant, scratch-resistant, semi-permanent use.

(3) Light weight: The wife uses very easily, the weight is only half of the iron pot, the use is light.

(4) No maintenance: Husbands use it with great confidence that high temperature will not burn, fall, and maintenance is not necessary.

Antibacterial property: It has natural photocatalyst antimicrobial effect and natural antimicrobial effect under natural light. It is hygienic and free from bacterial contamination.

Non-sticking effect: Good non-sticking effect, similar to the iron pot, but not completely non-sticking.

_Energy-saving: Time-saving and energy-saving, heat transfer speed is 7 times that of iron pot, is tens of times that of composite bottom steel pot and alloy pot, stir-frying can save energy.

Bioaffinity: It is human affinity and metal contact for a long time will not be allergic, medical stainless steel has replaced as a “human bone” implanted into the human body.

_Scope of use: Furnace and pottery magnet stove can be used.

Health: 99.75% high purity titanium metal is made of uncoated, which is the healthiest and safest metal pot.

_Non-sticky surface: Electrolytic grinding is more comprehensive and thorough, there is no harmful dust particles left by mechanical polishing, Electrolytic Grinding Titanium pan presents a fine concave and convex surface, which can improve the heat transfer speed and non-stickiness.

Image in the eyes of the public: Titanium is used for luxury items such as space shuttles, nuclear reactors, jewelry, eyeshelves, golf clubs and so on.

Titanium has such excellent properties, and it is also a very difficult metal to process. Understanding and understanding of titanium processing technology and processing means restrict relevant enterprises to enter this field. Until now, domestic titanium tableware and cooking utensils are still a virgin land, waiting for the development of insightful people. The titanium tableware and cooking utensils produced by this project technology overcome the rigid impression that pure titanium metal is difficult to display artistry and aesthetic feeling, and have bright colors, so that science and technology can be perfectly combined with life technology. Make millions of families really realize “to be healthy, use titanium pot!”

Application Status and Prospect of Titanium in Marine Engineering

Posted on by

I. Introduction

The ocean, which accounts for about 71% of the earth’s surface area, contains abundant resources. Exploiting and utilizing the ocean has become one of the directions of people’s efforts for many years. However, seawater is corrosive because it contains about 3.5% salt. In addition, some biological pollution in the ocean also accelerates the corrosion of seawater.

Titanium is a material with excellent physical properties and stable chemical properties. Titanium and its alloys have high strength, low specific gravity, seawater corrosion resistance and marine atmospheric corrosion resistance, which can well meet the requirements of people in marine engineering applications. Titanium has been widely used in the fields of offshore oil and gas development, harbour construction, coastal power station, seawater desalination, ships, Marine Fisheries and ocean thermal energy conversion after years of efforts by the titanium industry and marine engineering application researchers. At present, titanium for marine engineering has become one of the main fields of titanium civil applications.

II. Application Status

2.1 Offshore Oil and Gas Development

Oil is the lifeblood of a country’s economy. It is estimated that the world’s recoverable oil reserves are 300 billion tons, of which the seabed oil reserves are about 130 billion tons. The development of offshore oil began in the early 20th century. Its development has gone through a process from offshore to distant sea, from shallow to deep sea. Restricted by technological conditions and material development, oil and gas deposits extending directly from coast to shallow sea can only be exploited at first. Since the 1980s, stimulated by the energy crisis and technological progress, offshore oil exploration and development has developed rapidly, offshore oil development has rapidly advanced to the continental shelf, and a brand-new offshore oil industry has gradually formed. Offshore drilling platform is the base of offshore oil and gas exploration and exploitation, which marks the level of offshore oil and gas development technology. Offshore oil production equipment mainly includes oil production platform and ancillary equipment. The ancillary equipment includes crude oil cooler, oil lift pipe, pump, valve, joint and fixture, etc. These devices are in contact with sulfide, ammonia and chlorine in seawater and crude oil. Because of the excellent corrosion resistance of titanium in these media, the offshore oil platform pillars made of titanium were used in American oil fields in the early 1970s, and tubular heat exchangers and plate heat exchangers were made of titanium. Titanium tubular heat exchanger uses seawater as cooling medium to cool high temperature steam/oil mixture extracted from oil wells. Titanium plate heat exchanger also uses seawater as cooling medium to cool fresh water of crude oil in carbon steel heat exchanger. About 100 titanium heat exchangers have been used on drilling platforms in the North Sea Oilfield in the United States. The titanium components ordered by Hunting Oilfield Services in Aberdeen, Scotland, are said to be the first titanium high-pressure riser shaft in the world to be used in the Heidrum project of Conoco Norway.

Titanium drilling pipe has a long service life, its weight is only half that of stainless steel, but its flexibility is twice that of stainless steel, and its service life is 10 times that of steel. These excellent properties make titanium an excellent material for drilling near-circular and deep wells with great difficulty. The combined drilling tool with titanium drilling pipe can greatly reduce drilling time and total drilling cost. Grant Prideco, RTI Energy Systems and Torch Drilling Services in the United States first used titanium drilling pipes for industrial applications in 2000. The titanium drilling pipes manufactured and supplied by Grant Prideco and RTI Energy Systems are also equipped with steel tool joints provided by Grant Prideco Anti-fatigue Company. The joint is light in weight, flexible in use and can make the titanium drilling pipe strong.

Seawater pipeline system is an indispensable part of offshore oil exploitation. Because titanium has high corrosion resistance to seawater and its service life is 10 times that of steel system, the cost of titanium pipeline system is comparable to that of Cu-Ni system. Activated Metals Co. of America and Precision Tube Technology Co. Ltd. have jointly established a titanium tube technology company to produce a large-caliber titanium alloy tube. The alloy used in this kind of pipe is Ti-3Al-2.5V alloy with a diameter of 650mm, a wall thickness of 22-25mm, a length of 350m and a weight of 80-90t. It is planned to be used in offshore oil exploitation. Another U.S. company has made nearly 500 m long vertical shaft tubes by extruding seamless titanium alloy tubes with length of 15 mm, outer diameter of 600 mm and wall thickness of 25 mm, which have been used in an offshore drilling platform. It is said that the weight of the shaft pipe can be reduced by half, thus greatly reducing the ballast cost. In addition, it has high fracture toughness and long fatigue life.

It is reported that in the North Sea Oilfield Development Project in the United States, the amount of titanium used for floating structures and seabed fixtures on ships has increased compared with before. The demand for titanium for 24 floating bodies and 64 seabed fixtures is 50-100t for safety protection devices, 50-100t for connecting devices, 400-1000t for general lifting equipment and 1400-4200t for drill pipes. The corrosion of structural parts caused by biological pollution of offshore oil exploitation platforms is quite serious. A company in the United States has used a long casing made of titanium tubes to protect the parts on the platforms.

In the past few years, the application of titanium alloy components in oil drilling and coastal production has increased significantly. Titanium alloy components allow oil drilling to enter deeper waters and deeper wells, including higher temperatures and more corrosive (i.e., multi-salt) production environments.

For such applications, Ti-6Al-4V based alloys are the most suitable and the lowest cost considering their comprehensive properties. Seawater pipeline system is an indispensable part of offshore oil exploitation.

Application of Titanium Building Decoration Materials

Posted on by

Metal materials are used in buildings, especially in roofs. Copper is first used. Surface treated steel plates, aluminium, stainless steel and titanium are developed in turn. With the sustained development of national economy and the continuous improvement of people’s living standards, people’s requirements for urban buildings, especially for the aesthetics of buildings, are getting higher and higher. In recent years, architects have sought to use more advanced new building materials than traditional materials. Titanium metal has many excellent properties, which fully meet the many special performance requirements of building materials, so it is favored by architects and construction industry.

Japan is the first country to apply titanium to buildings, and it is also the country with the largest application of titanium in buildings. It is mainly used in the roof of buildings, curtain walls, ports, bridges, tunnels, exterior walls, doorplate, railings, pipes and so on. Britain, France, the United States, Spain, the Netherlands, Canada, Belgium and Switzerland all have examples of using titanium metal as roof and curtain wall in buildings. Sweden, Singapore and Egypt have also begun to use titanium metal in some new buildings. In 1997, the Guggenheim Museum in Bilbao, Spain, used titanium plates to construct curved surfaces. Abu Dhabi Airport also uses titanium, which uses hundreds of tons. It is the first airport in the world to use titanium as building materials.

China first proposed the application of titanium metal building is the National Grand Theatre, the first application is the Hangzhou Grand Theatre. Titanium-based buildings include the entrance hall of China National Nonferrous Engineering Design and Research Institute, the First Pavilion of Linping East, Hangzhou, the roof of Shanghai Circus Acrobatic Stadium and Dalian Saint-Asia Polar World. The titanium sculpture “Dolphin and Man” in Riverside Park of Baoji City, Shaanxi Province, the titanium sculpture “Qian Kun Ball” in Xingtai City Center Square, Hebei Province, and the titanium sculpture “Rooster Dawn” in Baoji City Pedestrian Street, Shaanxi Province are used for urban sculpture.

China’s titanium production technology is basically mature, production and design scale is large, but the sales market is not large, economic benefits are not ideal, mainly the lack of customer satisfaction with the technical and economic performance of good products. The present situation of titanium for construction in China is as follows:

  1. Single product: As a structural material, there are not enough varieties for users to choose. As a surface decoration material, there is no large-scale production enterprise of titanium surface treatment in our country at present, and the processing still stays in the production mode stage of manual workshops, which is not conducive to the large-scale use of titanium as decorative materials.
  2. Low grade: There is no high-quality products, not to mention the large supply of titanium and related composite materials. It can only produce some models, city carvings, crafts, etc. There is no high-grade surface decorative materials and production means.
  3. High price: Because there is no stable high-quality products, it is impossible to have a wide range of applications, resulting in a small amount of use, high prices, and more unfavorable to the promotion of use.
  4. Designer’s factor: There is no similar vocational training system in our country, and new materials are not stored in the thinking of architects after they are invented. As a result, the original design drawings of buildings seldom include titanium metal design, and the use is obviously less.

In recent years, with the progress of global oceanization and the falling price of titanium raw materials, the demand and application scope of titanium in the field of construction and decoration are constantly expanding. It is expected that the demand for titanium materials in the construction and decoration industries will reach more than 5000 tons in the next few years, and the demand for titanium materials in marine engineering and island construction will reach more than 5000 tons. The amount of titanium used in shipbuilding industry will exceed 5000 tons. However, there is no Titanium Material Manufacturing Enterprise specializing in building decoration in our country. It is only simple to apply industrial materials in the civil field, which is far from the market and industry demand. It is urgent to establish specialized production lines to meet the various professional needs in this field.

Titanium is a metal that can be produced in large quantities at the lowest price and is almost completely free from seawater corrosion. As a building material, the reflectivity of titanium material is relatively low, and it presents a light silver gray, with a charming natural metallic luster. Baoji Titanium Industry Research Institute will produce titanium materials for architectural decoration, mainly for roofs of buildings, followed by curtain walls, harbour facilities, bridges, submarine tunnels, exterior walls, decorations, small accessories, column decorations, outfits, monuments, signboards, doorposts, railings, pipelines, anti-corrosion coatings, etc. The project uses the existing domestic titanium plate and titanium coil as raw materials, uses plastic polishing and embossing technology to make the surface of the plate bright, uniform color and metal pattern; uses large area anodic oxidation coloring technology to colorize the surface of the plate, forming colorful colors to meet the needs of building and decorative materials.

Baoji Titanium Industry Research Institute has successfully applied titanium building decoration materials to large-scale buildings in China, and achieved a number of breakthroughs.

  1. For the first time, domestic titanium tapes were used for building decoration materials.
  2. For the first time, large-area color coating was used to realize the multi-color decoration of titanium.
  3. For the first time, the architectural decoration of titanium has been realized.
  4. For the first time, the application area of multi-color titanium decorative materials in China is the largest.

Why does titanium alloy have to be used in materials for air transport aircraft?

Posted on by

We are often exposed to air transport, such as air cargo, such as flying. When you see an airplane, you may have a question: What is it made of? Why can you carry so many heavy cargo and fly so high? We looked down with doubts.

Introduction of Titanium

Only in 1948 did DuPont produce titanium sponge in tons by magnesium method, which marked the beginning of industrialized production of titanium sponge. Titanium alloys are widely used in various fields because of their high specific strength, good corrosion resistance and high heat resistance.

Titanium is abundant in the crust, ranking ninth, far higher than copper, zinc, tin and other common metals. Titanium is widely found in many rocks, especially in sandstone and clay.

CHARACTERISTICS OF TITANIUM

High strength: 1.3 times as much as aluminium alloy, 1.6 times as much as magnesium alloy, 3.5 times as much as stainless steel, champion of metal materials.

High thermal strength: the use temperature is several Baidu higher than that of aluminium alloy, and it can work for a long time at 450-500 C.

Good corrosion resistance: acid resistance, alkali resistance, atmospheric corrosion resistance, pitting corrosion, stress corrosion resistance is particularly strong.

The low temperature performance is good: the titanium alloy TA7 with very low interstitial elements can maintain a certain plasticity at – 253 C.

High chemical activity: high chemical activity at high temperature, easy to react with hydrogen, oxygen and other gaseous impurities in the air to form a hardened layer.

The thermal conductivity of titanium alloys is about 1/4 of nickel, 1/5 of iron and 1/14 of aluminium, while the thermal conductivity of titanium alloys is about 50% lower than that of titanium. The elastic modulus of titanium alloy is about 1/2 of that of steel.

III. CLASSIFICATION AND USE OF TITANIUM ALLOYS

Titanium alloys can be divided into heat resistant alloys, high strength alloys, corrosion resistant alloys (Ti-Mo, Ti-Pd alloys, etc.), low temperature alloys and special functional alloys (Ti-Fe hydrogen storage materials and Ti-Ni memory alloys).

Although titanium and its alloys have not been used for a long time, they have gained many honorable titles because of their excellent properties. The first title won was “Space Metal”. It has light weight, high strength and high temperature resistance, and is especially suitable for manufacturing aircraft and various spacecrafts. At present, about three-quarters of the world’s titanium and titanium alloys are used in the aerospace industry. Titanium alloys have been used in many parts originally made of aluminium alloys.

IV. Aviation Applications of Titanium Alloys

Titanium alloys are mainly used for manufacturing materials of aircraft and engines, such as forging parts of titanium fans, compressor discs and blades, engine hood, exhaust devices, and structural frame parts of aircraft girders and diaphragms. Spacecraft mainly utilizes the high specific strength, corrosion resistance and low temperature resistance of titanium alloy to manufacture various pressure vessels, fuel tanks, fasteners, instrument straps, frameworks and rocket shells. Titanium alloy plate weldments are also used in artificial earth satellites, lunar module, manned spacecraft and space shuttles.

In 1950, the U.S. first used F-84 fighter bomber as non-load-bearing components such as rear fuselage heat insulation plate, air guide hood and tail hood. Since the 1960s, the use of titanium alloys has shifted from the rear fuselage to the middle fuselage, partially replacing structural steel to manufacture important load-bearing components such as partitions, beams, flaps and slides. Titanium alloys have been widely used in civil aircraft since the 1970s. For example, the amount of Titanium used in Boeing 747 passenger aircraft is more than 3640 kg, accounting for 28% of the aircraft weight. With the development of processing technology, titanium alloys are also used in rockets, satellites and spacecraft. The more advanced the aircraft, the more titanium it uses. Titanium alloy is used in F-14A fighter aircraft, accounting for about 25% of the aircraft weight; F-15A fighter aircraft is 25.8%; Titanium used in the fourth generation fighter aircraft is 41%, and Titanium used in F119 engine is 39%, which is the highest Titanium used aircraft at present.

5. Reasons for the extensive application of titanium alloys in aviation

The highest speed of modern aircraft has reached more than 2.7 times the speed of sound. Such a fast supersonic flight would cause the aircraft to rub against the air and generate a lot of heat. When the flight speed reaches 2.2 times the speed of sound, the aluminium alloy can’t stand it. High temperature resistant titanium alloys must be used. When the thrust-weight ratio of aero-engine increases from 4 to 6 to 8 to 10 and the outlet temperature of compressor increases from 200 to 300 to 500 to 600, the original low-pressure compressor disk and blade made of aluminium must be replaced by titanium alloy.

In recent years, scientists have made new progress in the research of properties of titanium alloys. The original titanium alloy consisting of titanium, aluminium and vanadium has a maximum working temperature of 550 ~600 C, while the newly developed TiAl alloy has a maximum working temperature of 1040 C. Using titanium alloy instead of stainless steel to manufacture high pressure compressor disc and blade can reduce the structural weight. For every 10% reduction in weight, the aircraft can save 4% of its fuel. For a rocket, a range of 15 km can be increased for each weight reduction of 1 kg.

VI. Analysis of Machining Characteristics of Titanium Alloys

Firstly, the thermal conductivity of titanium alloy is only 1/4 of steel, 1/13 of aluminium and 1/25 of copper. Because of the slow heat dissipation in the cutting area, which is not conducive to heat balance, the heat dissipation and cooling effect is very poor in the cutting process, which is easy to form high temperature in the cutting area. After processing, the parts deform and rebound greatly, resulting in increased cutting tool torque, rapid edge wear, and reduced durability.

Secondly, the low thermal conductivity of titanium alloy makes the cutting heat accumulated in a small area near the cutting tool not easy to emit, the friction of the rake face increases, the chip removal is not easy, the cutting heat is not easy to emit, and the tool wear is accelerated.

Introduction to the Categories and Basic Knowledge of Titanium Oxides

Posted on by

Titanium oxides can be basically divided into three kinds: titanium dioxide, titanium tetrachloride and barium metatitanate. Their application is very extensive, but their development space is limited because of the high cost. However, we believe that in the near future, with the continuous development of titanium industry technology, titanium oxides will get greater development.

A. Titanium dioxide: It is a white powder, the best white pigment, commonly known as titanium dioxide.

1. Titanium dioxide has strong adhesion and is not easy to change chemically. It is always white. Special attention should be paid to the non-toxicity of titanium dioxide. It has a high melting point and is used to make refractory glass, glaze enamel, pottery, high-temperature experimental utensils and so on.

2. Titanium dioxide has the covering property of lead white and the durability of zinc white. Titanium dioxide is usually added to paint to make high-grade white paint; additives are added to paddles in paper industry; and matting agents for man-made fibers in textile industry.

3. In order to lighten the color of plastic and soften the artificial mercerization, titanium dioxide is sometimes added. In the rubber industry, titanium dioxide is also used as filler for white rubber.

B. Titanium tetrachloride: Titanium tetrachloride is an interesting colorless liquid with a melting point of 250 K and a boiling point of 409 K. It has a stimulating odor and emits a lot of white smoke in wet air. This is because it hydrolyzes and produces white titanium dioxide hydrogel (TiCL4+3H2O= H2TiO3+4HCL). In military affairs, titanium tetrachloride is conveniently used as artificial smoke agent. Especially in the ocean, there is a lot of water and gas. When titanium tetrachloride is released, the smoke is like a white Great Wall, blocking the enemy’s sight. In agriculture, people will use the fog formed by TiCL4 to reduce the loss of surface heat at night and protect vegetables and crops from the danger of cold and frost.

C. Barium metatitanate: It is made by melting titanium dioxide and BaCO3 together. Barium titanate crystals have the characteristic that when pressed, they produce electric current, and when electrified, they change their shape. Therefore, people put barium titanate in the ultrasonic wave, it will generate current when it is pressed, and the magnitude of the current generated by it can be used to measure the strength of the ultrasonic wave. On the contrary, ultrasonic waves can be generated by passing through it with high frequency current. It is now used in almost all ultrasound instruments. For example, railroad workers put it under the rails to measure the pressure when the train passes; doctors use it to make pulse recorders and so on. With the development and utilization of titanate, it is more and more widely used in non-linear components, dielectric amplifiers, computer memory elements, micro capacitors, aviation, semiconductor, optical instruments, reagents and so on.

TECHNOLOGY OF COLD ROLLED Gr5 TITANIUM ALLOY TITANIUM TUBE

Posted on by

Gr5 titanium alloy is one of the most widely used titanium alloys at present. It has high strength and good corrosion resistance. However, it is difficult to find seamless titanium tubes made of Gr5 in the domestic and foreign seamless titanium tube market.

Gr5 titanium is mainly made of sheet metal, and Gr5 titanium pipes on the market are mainly made of high-strength thick-walled pipes by hot extrusion or oblique piercing. This warm rolling process needs to improve the traditional roll, i.e. installing induction heating device on the pipe mill. This kind of processing equipment has complex structure, complicated process and high production cost. The main reason for the present situation is the high strength of Gr5 titanium alloy and the difficulty of cold rolling forming. In order to solve the key technology of cold rolling of Gr5 seamless tube, a series of studies have been carried out jointly by schools and enterprises. If the direct cold rolling process is used to produce high strength titanium alloy pipes, not only the production cost is greatly reduced, but also the requirements for high performance applications of titanium alloys can be met.

The billet was rolled to 70% of the total deformation by two and three passes of rolling respectively. Vacuum annealing was carried out between passes at 800 C for 1 h. The cooling method was air cooling to room temperature after furnace cooling to 500 C. The changes of structure and properties were observed. It is concluded that:

In the case of small deformation, the wall thickness deviation is small and the surface roughness decreases gradually; in the case of large deformation, the wall thickness deviation is large, which will affect the wall thickness deviation of the tube obtained by subsequent pass rolling.

With the same total deformation, the more rolling passes, the greater elongation and hardness of the pipe, and the higher strength. Good comprehensive performance.

When rolling with large deformation, the flow of material is strip-like, and when rolling with small deformation, the flow of material is bundle-like. Under the same conditions of heat treatment between passes and subsequent rolling process, the structural distortion of tube produced by large deformation billet is more serious.

The anisotropy of pipe is not affected by small deformation billet, and the anisotropy of mechanical properties fluctuates in multi-pass rolling.

Method of Improving Tapping Efficiency of Titanium Alloy

Posted on by

With the development of processing technology, in recent years, titanium alloys have been widely used in the manufacture of compressor section, hood, exhaust device and other parts of aircraft engine, as well as the manufacture of structural frame parts such as beam diaphragm of aircraft. Tapping of titanium alloys, especially small holes below M6mm, is quite difficult. The main reason is that the chip is small and easy to bond with the blade and workpiece, resulting in large surface roughness and large torque.

When tapping, improper selection and operation of taps can easily lead to work hardening, low processing efficiency and breakage of taps. The solutions are as follows:

The number of teeth should be less than that of standard taps, usually 2-3 teeth. Cutting taper angle should be large, taper part is generally 3-4 thread length. In order to facilitate chip removal, the negative inclination angle can also be grinded in the cutting cone part. Choose short taps as far as possible to increase the rigidity of taps. The inverted cone part of the tap should be enlarged appropriately compared with the standard to reduce the friction between the tap and the workpiece.

In order to reduce the hardening of the bottom hole, roughing drill is first used and reaming drill is used to ream the bottom hole. For threads with pitches of 0.7-1.5mm, the size of bottom hole can be machined to the top difference of standard thread bottom hole stipulated by the national standard, and it can be increased by 0.1mm.

If the position of the screw hole and the shape of the workpiece are not limited, machine tapping should be adopted as far as possible to avoid the work hardening caused by uneven feeding of manual tapping and stopping in the middle.

Titanium alloy is an ideal material for aircraft and engine because of its high specific strength, good mechanical properties and corrosion resistance. However, its poor machinability has restricted its application to a large extent for a long time.

Processing of Titanium Alloys such as Titanium Bar, Titanium Wire, Titanium Plate and Titanium Forging

Posted on by

What processes and methods are included?

Titanium ingots are manufactured into various processing materials (titanium rods, wires, forgings, plates, tubes and profiles) by means of plastic processing (including cold and hot processing), which not only makes titanium metal easy to use, but also improves its structure and properties. It can also be used to make parts of various shapes by near net forming process (casting and powder metallurgy). Generally speaking, the properties of powder or castings are not as good as those of processed materials, but they can also be improved by hot isostatic pressing. Powder metallurgy process can also produce alloys that are difficult to produce by smelting process, such as particle reinforced alloys. In addition, welding and composite materials can also be used to achieve the desired products and properties.

The flow chart of the concise production process of the processed material is as follows:

Features of Titanium

Posted on by

1. Low density, high specific strength

Titanium has a density of 4.51g/cm3, higher than aluminium and lower than iron, copper and nickel, but the specific strength of Titanium is the highest among metals.

2. Corrosion resistance

Titanium is a very active metal. Its equilibrium potential is very low and its thermodynamic corrosion tendency in medium is high. In fact, titanium is very stable in many media, such as oxidizing, neutral and weak reducing media. This is because titanium and oxygen have a great affinity. In air or medium containing oxygen, a dense, strong adhesion and inert oxide film is formed on the surface of titanium, which protects the titanium matrix from corrosion. Even due to mechanical wear, it will soon heal or regenerate. This indicates that titanium is a metal with strong passivation tendency. Titanium oxide films at medium temperatures below 315 keep this characteristic all the time.

In order to improve the corrosion resistance of titanium, surface treatment technologies such as oxidation, electroplating, plasma spraying, ion nitriding, ion implantation and laser treatment have been developed. Titanium oxide film plays a protective role. The desired corrosion resistance was obtained. A series of corrosion-resistant titanium alloys, such as Ti-Mo, Ti-Pd, Ti-Mo-Ni, have been developed to meet the needs of metal materials in the production of sulphuric acid, hydrochloric acid, methylamine solution, high temperature wet chlorine and high temperature chloride. Titanium castings are made of Ti-32 molybdenum alloy. Ti-0.3 molybdenum-0.8 nickel alloy or Ti-0.2 palladium alloy are used locally in the environment where crevice corrosion or pitting corrosion often occurs. Good results are obtained.

3. Good heat resistance

The new titanium alloy can be used for a long time at 600 C or higher.

4. Good low temperature resistance

The strength increases with the decrease of temperature, but the plasticity does not change much. The ductility and toughness are maintained at – 196 – 253 ~C. It avoids the cold brittleness of metals and is an ideal material for cryogenic containers, tanks and other equipment.

5. Strong anti-damping performance.

Titanium metal is subject to mechanical vibration. Compared with steel and copper metal, its own vibration attenuation time is the longest. Using this property of titanium, it can be used as vibration element of tuning fork, medical ultrasonic crusher and vibration film of advanced loudspeaker.

6. Non-magnetic and non-toxic

Titanium is a non-magnetic metal, which will not be magnetized in a large magnetic field. It is non-toxic and has good compatibility with human tissues and blood, so it is adopted by the medical profession.

7. Tensile strength is close to yield strength.

This property of titanium shows that its yield strength ratio (tensile strength/yield strength) is high, which indicates that the plastic deformation of metal matrix is poor. Because the ratio of yield limit of titanium to the amount of elastic film is large, the resilience of titanium during forming is great.

8. Good heat transfer performance

Although the thermal conductivity of metallic state is lower than that of carbon steel and copper, the wall thickness of titanium can be greatly reduced due to its excellent corrosion resistance. The heat transfer between surface and steam is dropwise condensation, which reduces the thermal resistance. Non-scaling on the surface of titanium can also reduce the thermal resistance, thus greatly improving the heat transfer performance of titanium.

9. Low modulus of elasticity

The elastic modulus of titanium at room temperature is 106.4 MPa, which is 57% of that of steel.

10. Inhalation performance

Titanium is a metal with very active chemical properties. It can react with many elements and compounds at high temperature. Titanium gas absorption mainly refers to the reaction with carbon, hydrogen and oxygen at high temperature.