Thermoelectric materials made by Powder metallurgy

Powder metallurgy method making thermoelectric materials bismuth telluride (Bi2Te3) alloy, working temperature isclose to 450 ℃ can be used in the manufacture of household refrigerator, air conditioner, small detectors and sensors, etc. Bismuth telluride with a small amount of antimony telluride (Sb2Te3) alloying can form P type semiconductor solid solution, and with a small amount of bismuth selenide (Bi2Se3) alloying can form N type semiconductor solid solution. Bismuth telluride, it and other components to forming alloy have highly anisotropic structure. the most commonly used method making bismuth telluride alloy is single crystal directional crystallization. But this method is low productivity, segregation, and poor mechanical properties.

Canada after three years development, has developed a method of of producing bismuth telluride alloy by powder
metallurgy. It is mechanical alloying 2-5 mm diameter granular pure elements (such as Bi, TeSeSb) powder in a ball mill, after about 3h can be obtained for 5~10 m particle size alloy powders. Powder is cold pressed under the pressure of 360 mpa , compact body relative density of 80%, And hot extrusion in inert atmosphere into the 963.5 mm bar, extrusion temperature 420-490 ℃. The extrusion speed of 2 mm/min, products is dense after hot extrusion. Although extrusion materials is polycrystalline, but have no difference thermoelectric performance with single crystal material.

Material compression strength is 105 mpa, and the single crystal materials is only 20 mpa, grain boundaries hinder crack propagation of polycrystalline materials. This is helpful to improve its mechanical properties and the reliability of the thermoelectric devices. Manufacturing thermoelectric materials of powder metallurgy method can reduce the production cost, increase productivity, and has no damage.

breaking pads made with powder metallurgy

With increasing car ownership in our country, the production of brake pad is also increasing year by year. Brake pads is the key components of train brake system. The quality of the high-speed rail brake pads is directly related to the train speed can slow down and stop in time, called "the patron saint of life".
With the rapid development of high-speed railway in China, its various performance requirements also corresponding increase, especially puts forward more strict requirements on braking performance. The braking power and speed of the train is cubic relationship, that is to say, the train speed double then braking power requires increased 8 times. High-speed train braking force mainly include electric braking force and friction, the friction braking is train safe parking final guarantee. Friction braking force comes from the friction between the brake disc and brake pads on the braking system. And in the braking system brake pads performance has very big affect on the train braking effect. Brake pad materials at home and abroad mainly experience metal, alloy and powder metallurgy etc.
In the world there is only a few countries such as Germany, France and Japan can produce high-speed train brake pad. Among them Germany Knorr company Monopolies more than 80% of the global high iron brake pads market. High-speed trains in China since its opening,  the brake pads of braking system relies on imports for long-term. Import brake pads has problems aush as high price, long cycle of supply, spare parts supply not in time and poor after-sales service. High-speed rail brake pads is n technology protection period before 2012, has been importing foreign products. In recent years the domestic represented by Tianyishangjia and PuRan private enterprises gradually enter the field of high-speed rail brake pads. Tianyishangjia in September 2013 got seven models 5 types of brake pads CRCC certificate of railways product, PuRan got CRCC certification in 2014. In 2015, BoShen tool has finished the high-speed train brakes 1:1 brake friction wear performance test.

Powder metallurgy technology can effectively solve the difficulty in processing and forming of TiAl alloy

In recent years, in order to promote the high temperature high performance high titanium niobium alloy engineering technology and industrialization process, our country developed with independent intellectual property rights of a new generation of aerospace engine materials used high temperature high performance high titanium niobium alloy material, will soon enter the stage of industrialization. This technology will make our country aerospace engine materials the world leading level. High titanium niobium alloy is a research direction of innovation in our country, has the world's first high temperature alloy patent, led the world in the field of research and development, is a milestone in the development of titanium aluminum alloy, marked the titanium aluminum intermetallic compound research field in China as the international leading position. 
Our country has put a titanium alloy research included in the national 863 high technology and new material development.

After years of efforts, in the alloy microstructure, deformation characteristics and the effect of adding elements and alloy preparation technology and so on has carried on the fruitful work. There have been many studies of titanium aluminum alloy papers published in journals and conferences both at home and abroad.

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