New processes, technologies, applications, development status and competition pattern of titanium and titanium alloys

1. Brief introduction to the properties of titanium and titanium alloys

1.1 Titanium introduction:

Titanium is a new material with the advantages of low density, high specific strength, heat resistance and corrosion resistance. Its weight is only half of that of iron, but its mechanical properties such as hammering, drawing, etc. are almost equal to that of copper. Generally speaking, with the decrease of temperature, the impact resistance of metal will decline, but titanium is on the contrary. The lower the temperature is, the harder titanium will become, and superconductivity will occur when the critical temperature is reached.

1.2 Introduction to titanium alloy:

Titanium alloy and titanium have similar properties to some extent, with the characteristics of low density and high strength. In addition, their mechanical properties are very excellent, and their corrosion resistance is strong. Moreover, its thermal strength is higher than that of aluminum alloy, and its mechanical properties have little change at low and ultra-low temperatures.

2. New Process, Technology and Application of Titanium

2.1 Preparation method of titanium

Although titanium is relatively abundant in nature, it is also a rare metal because it is dispersed and difficult to extract. At present, the preparation of titanium can be divided into two categories: thermal reduction method and molten salt electrolysis method.

(1) Preparation of titanium by thermal reduction

The thermal reduction method is to reduce titanium from titanium compounds such as TiCl 4, TiO 2, K 2TiF 6, etc. by using strong reducing agents such as Li, Na, Mg, Ca and their hydrides at a certain temperature. According to the different titanium compounds, the technologies for preparing titanium by thermal reduction can be divided into three categories:

① Oxidation and reduction methods of titanium chloride, such as Kroll method, Hunter method, Armstrong method and EMR method;

② Oxidation and reduction methods of titanium oxides, such as OS method, PRP process, MHR method, etc;

③ Oxidation reduction method of titanate.

At present, only Kroll method and Hunter method can be successfully applied in industrial production. Kroll method uses magnesium metal to replace titanium in chloride, Hunter method uses sodium metal to replace titanium in chloride. In addition, the Armstrong method developed by Chicago International Titanium Powder Company in the United States is similar to the Hunter method in its preparation method. It also uses sodium reductant to purify metal titanium. The United States has begun to use this method for pre production in factories.

(2) Preparation of titanium by molten salt electrolysis

In 1959, Kroll predicted that molten salt electrolysis would replace Kroll process as the mainstream method of titanium production in the next 5-10 years. Over the years, scientific research institutions and laboratories at home and abroad have developed a total of more than ten new technologies for preparing titanium by molten salt electrolysis, which can be divided into the following three categories according to raw materials: ① electrolysis of titanate; ② Electrolysis of titanium chloride; ③ Electrolytic methods of titanium oxides include FFC Cambridge method, MER process, USTB process, QIT process, SOM process and ionic liquid electrolysis method.

2.2 New uses of titanium

Since the 1940s, the use of titanium has developed rapidly, and it is widely used in aircraft, rockets, missiles, artificial satellites, spaceships, warships, military, medical and petrochemical fields. The latest research found that the human body contains a certain amount of titanium, which can stimulate phagocytes and strengthen the immune function. Therefore, many laboratories are committed to the development and application of biological titanium.

3. New technology and application of titanium alloy

3.1 Preparation method of titanium alloy

Traditional processing of titanium alloys generally adopts smelting and casting technologies. The latest processing technologies are divided into the following:

(1) Near net shaping technology;

(2) Wire friction welding technology;

(3) Superplastic molding technology;

(4) Computer simulation technology of material preparation and processing process.

Near net forming technology includes laser forming, precision casting, precision die forging, powder metallurgy, spray forming and other methods. Powder metallurgy is a new process that uses titanium powder or titanium alloy powder as raw materials, through molding and sintering, to manufacture titanium parts. The first is to produce powder. Generally, mechanical alloying method is adopted, and the ball mill is used to strongly impact, grind and stir the raw materials. Then, the alloy that has formed powder is pressed and formed. There are two pressing methods, namely pressure forming and non pressure forming. The purpose of this step is to make the pressed embryo of certain shape and size, and make it have a certain density and strength. Then, the preform is sintered by spark plasma sintering. The specific sintering power supply and pressing pressure are applied to the sintered powder by using the upper and lower die punches and the energized electrodes. After the discharge activation, thermoplastic deformation and cooling, high-performance titanium materials are prepared. Then the titanium alloy after plasma sintering is subject to subsequent treatment, generally heat treatment or plastic processing.

3.2 New applications of titanium alloys

Titanium alloys were widely used in the aerospace field in the early days, mainly for making aircraft engines or pneumatic components. Later, with the continuous development of technology, titanium alloy has entered the lives of ordinary people, and it has also been used in factories or household devices. Now, countries and institutions are racing to develop new titanium alloys with the characteristics of low cost and high performance. In recent years, the new development of titanium alloys mainly focuses on the following five aspects.

(1) Medical titanium alloy

Titanium alloy has low density and good biocompatibility, so it is an ideal medical material, which can even be implanted into human body. Titanium alloy previously used in medical field contains vanadium and aluminum, which will cause harm to human body. However, recently, Japanese scholars have developed a new type of titanium alloy with good biocompatibility, but at present, this alloy has not been mass produced. It is believed that in the near future, this kind of high-quality alloy can be widely used in daily life.

(2) Flame retardant titanium alloy

The titanium base alloy which can resist combustion under certain pressure, temperature and air flow rate is flame retardant titanium alloy. The United States, Russia and China have developed new flame retardant titanium alloys one after another. The United States applies these flame retardant titanium alloys to engines. Because these titanium alloys are insensitive to combustion, they can greatly improve the stability of engines.

(3) High strength and toughness β type

β Type I titanium alloy has the characteristics of high strength, good weldability and excellent cold and hot workability. The researchers used this rule to prepare β The characteristics of T - type titanium alloy are very obvious: good flexibility, good plasticity and good weldability. The mechanical properties of the composites are greatly improved after solution aging treatment. At present, Japan and Russia have prepared such titanium alloys.

(4) Titanium aluminum compound

Compared with ordinary titanium alloys, titanium aluminum compounds have good high-temperature properties, oxidation resistance and creep resistance, and their density is smaller than that of ordinary titanium alloys. These excellent characteristics doomed the titanium aluminum compound to set off a new alloy upsurge. At present, this new titanium aluminum compound alloy has been synthesized in the United States and is in mass production.

(5) High temperature titanium alloy

Titanium alloys prepared by combining rapid solidification method with powder metallurgy method using fiber or particle reinforced composites have excellent high temperature mechanical properties. The service temperature limit of high temperature titanium alloy is far higher than that of ordinary titanium alloy. At present, the United States has prepared a new type of high-temperature titanium alloy.

(6) Titanium nickel alloy

The alloy composed of titanium and nickel is called "memory alloy". This alloy is made into a predetermined shape. After shaping, if it is deformed by external force, it can recover its original appearance as long as it is slightly heated. This alloy can be used in various fields such as instruments, electronic devices, etc.

4. Current development status and competition pattern of titanium alloy materials in China

Titanium alloys refer to a variety of alloy metals made of titanium and other metals. In recent years, China has frequently issued policies to encourage the research, development, production and application of titanium alloy materials. In the global market, titanium alloy materials are mainly used in aviation industry, national defense and military industry and other industries. Among them, the application demand in the aviation industry is the largest, accounting for about 50%, mainly for aircraft and engine manufacturing. In the demand structure of titanium materials in China, titanium processing materials are mainly used in the chemical industry, while the proportion of titanium materials for aerospace in China is only 20%, indicating that there is still great potential in the market of titanium materials for aerospace in China. At present, in the high-end titanium alloy field, there are few enterprises that can mass produce military aviation titanium alloy bars and wires in China, presenting a "duopoly" competition pattern.

1. Policies to encourage the development of titanium alloy materials

Titanium alloys refer to a variety of alloy metals made of titanium and other metals. Many countries in the world have realized the importance of titanium alloy materials, and have carried out research and development on them, and have been applied in practice. In recent years, China has also frequently issued policies to encourage the research, development, production and application of titanium alloy materials. In 2019, according to the information disclosed in the Guiding Catalogue for Industrial Restructuring (2019 Draft for Comments), high-performance ultra-fine, ultra coarse, composite structure cemented carbide materials and deep processed products, low modulus titanium alloy materials, corrosion resistant titanium alloy materials, titanium alloy fasteners for aerospace, etc. were listed as encouraged projects for industrial restructuring.

2. Titanium alloy materials are mainly used in aerospace and military industries

In the global market, titanium alloy materials are mainly used in aviation industry, national defense and military industry and other industries. Among them, the application demand in the aviation industry is the largest, accounting for about 50%, mainly for aircraft and engine manufacturing.

In the demand structure of titanium materials in China, titanium processing materials are mainly used in the chemical industry. Compared with the world, the most important difference is in the aviation field. The global aviation titanium materials always account for about 53% of the total demand for titanium materials, while the domestic aerospace titanium materials account for only 20%, indicating that there is still great potential in the aviation titanium materials market in China.

3. The domestic high-end titanium alloy market presents a "duopoly" competition pattern

In the domestic titanium alloy market, the enterprises that can mass produce titanium alloy bars and wires for military aviation are mainly: Western Superconductor, Baoti Co., Ltd. and Hunan Jintian Titanium Industry Technology Co., Ltd.

4. Wide Demand Prospect of Titanium Materials for Aerospace

From 2009 to 2017, the annual compound growth rate of titanium sales for aerospace in China was 16%. Considering that the current proportion of titanium materials for aerospace in China is far lower than 50% of the total demand for titanium materials worldwide, assuming that the compound growth rate will remain unchanged in the next few years, the demand for titanium materials for aerospace industry in China will reach 25000 tons by 2025.

5. Conclusion

Titanium has many incomparable advantages over other metals. With the progress of society and the development of science and technology, the application of titanium and titanium alloys will be more extensive. The demand for titanium and titanium alloys will increase day by day, and the high production cost is one of the main reasons limiting the promotion and use of titanium and titanium alloys. Therefore, the development and application of low-cost, large-scale and eco-friendly continuous production processes can make titanium and titanium alloys more widely used.