The Metal Zirconium Tungstate Composite Material
Thermal expansion and contraction are common physical phenomena.
However, there are some materials which do not act according to common sense and show the opposite phenomenon of thermal expansion and cold expansion, such materials are known as negative thermal expansion materials, and zirconium tungstate is one of the negative thermal expansion materials.
The results show that the zirconium tungstate ZrW2O8 has a stable negative thermal expansion performance in the range of 0.3 to 1050.0K in the temperature range, negative thermal expansion coefficient alpha can reach -9 * 10-6K-1, and is isotropic. Therefore, zirconium tungstate can be used alone as a heat shrinkable material, and can also be mixed with other materials to form composite material.
Zirconium tungstate metal substrate is using a powder metallurgy method principle, adding zirconium tungstate composite material in the metal. Because of its excellent conductivity and thermal conductivity, the composite of zirconium tungstate and metal can make the composites not only have low thermal expansion characteristics, but also have excellent properties of metals. This kind of metal-based zirconium tungstate composite with low thermal expansion and high thermal conductivity has wide application prospect in microelectronics, the metal material, which is usually compounded with zirconium tungstate, is predominantly aluminum, titanium, and copper, and the object is more aluminum.
In the field of microelectronics, such as aerospace industry structure components, electronic packaging, measuring instruments, optical devices, sensitive components, satellite antennas and other high-precision devices, it often requires materials with lower thermal expansion coefficients, such as below 15 x 10-6K-1 or even below 10 * 10-6K-1, so that the material can maintain dimensional stability when subjected to temperature changes, and the general negative thermal expansion material "aluminum" is difficult to achieve this requirement. Therefore, some scholars have combined aluminum and zirconium tungstate into aluminium based zirconium tungstate composite, the thermal expansion coefficient was reduced to 8.7 * 10-6K-1, and the bottleneck problem was solved easily.
The traditional preparation methods of metal base tungstic acid composite material are heating sintering and pressing. Aluminum alloy zirconium tungstate composite material was successfully prepared by powder metallurgy method and sintered by pulse current sintering of aluminum and zirconium tungstate. Dai Enbin and other scholars at Central South University successfully prepared ZrW2O8/6013Al composites by pressure melt infiltration method, the results show that the coefficient of thermal expansion of aluminum based zirconium tungstate composite is lower and the performance is more stable than aluminum alloy.
The low heat metal based zirconium tungstate composite can greatly improve the thermal shock resistance of the material, when the material is used in the changing temperature condition, the dimension stability is maintained and the service life of the material is improved, compared with the traditional low expansion alloy, it has the advantages of self-evident. Of course, there has not been a major breakthrough in the preparation of zirconium tungstate. The difficulty of preparation and high cost is the main problem. With the development of China's material industry, it is believed that the cost of zirconium tungstate will be solved soon.
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