Except reduction temperature, the thickness of the material layer will affect tungsten powder granularity and distribution. Theoretically, increasing thickness of the material reduction of tungsten powder tungsten powder particles loaded boat will thicken; and in turn reduce the material thickness of tungsten powder particle size means the boat will be relatively finer. However, in actual production, thick boat loading volume will cause the powder particle size distribution is widened, especially caused bimodal, multimodal and tail peak. In addition, WC powder of different particle size distribution produced by the hardness of tungsten carbide button as the particle size distribution will be broadened and significantly reduced. The reason is that the particle size distribution wider tungsten powder there will be large differences in the thickness of the particles, the difference in the process of carbonation will cause uneven WC grain growth, which make the same batch of powder in both the coarse particles have a single crystal by the fine-grained particles composed of polycrystalline. When the carbonization temperature is low, the fine particles carbonization completely, while the coarse particles are non-complete; when the high temperature carbonization, coarse grains are also complete carbonized, but the fine particles becomes single crystal and grows up.

In the production of tungsten carbide buttons, use single crystal and polycrystalline particles coexisted WC powder, mixed alloy material crushing prolonged, single crystal grains not crushed easily or crushed consistency is poor. Thus, by optimizing the production process of tungsten powder, such as reduction temperature control, carbonization temperature, the amount of loading the boat, etc., to fabricate homogeneous single crystal or polycrystalline WC powder, which is beneficial for improving the performance of tungsten carbide buttons.

Before HIP process, tungsten powder mixed with a certain amount of copper, cold isostatic pressing, low temperature pre-sintered to give semi-finished copper by infiltration. It uses argon (Ar) as pressure transmission medium, temperature control (tungsten-rhenium thermocouple measurement), pressure, dwell time and other relevant parameters, before and after the HIP process copper tungsten contact material hardness, density, bending strength and conductivity of comparative measurements. The density uses conventional Archimedes drainage method; the hardness uses Rockwell hardness HRB and refers to Brinell hardness HB; flexural strength is measured by GB electrical contact material basic performance; electrical conductivity is measured by eddy current conductivity tester.

The experimental result shows that HIP densification mechanism of tungsten copper contacts is similar to the cast alloy, which removes internal defects by deformation - closed - diffusion under high temperature and high pressure and achieves completely densification. Therefore, it requires after-infiltrated material should have good closure, all internal defects, osteoporosis and so can not in communication with the outer surface. If all the defects can not be guaranteed enclosed inside the blank in the process of infiltration, the density after HIP process changes little, even no change. In addition, HIP treatment effect is also related to the content of copper. When the HIP temperature reaches a temperature close to the melting point of copper, its surface will be leaking copper beads phenomenon. Overall, HIP process can promote tungsten copper contact completely densification, which remarkably improves the mechanical and physical properties, and effectively solves dispersion and reliability.

Tungsten carbide button mainly consist of tungsten carbide (WC) and cobalt (Co), which has high hardness, high strength, high melting point, excellent wear resistance and chemical stability. So it has a broad application prospect in oil exploitation and other geological drilling industries. Tungsten carbide button inlayed on drill bit to impact, rotate, crush and shear the rock. Since most of the drilling depth deeper, dig a longer length, and some may reach thousands of meters. Tungsten carbide button if other reasons due to wear, breakage or failure occurs repeatedly replace the drill bit will seriously affect the overall drilling efficiency.

Therefore, it put higher requirements tor the hardness and wear resistance of tungsten carbide buttons. And both of mechanical and physical properties depend on its content and structure. The original properties of WC powder, especially physical properties directly determine the structure of tungsten carbide buttons. The quality of WC powder is inseparable from tungsten powder reduction, in order to achieve WC powder with high quality, we need to combine tungsten powder reduction parameters and optimize, which can remarkably improve tungsten carbide button properties.

From the preparation process of WC powder, its basic process is APT (Ammonium Paratungstate) → Hydrogen (H2) pre-reducing → Blue tungsten → Hydrogen (H2) reducing → Tungsten (W) powder → Carbonizing → Tungsten carbide (WC) block → Crushing → Sieved and granulation → WC powder. Through experimental analysis, WC powder during the preparation of the whole of the main factors including temperature, material thickness and grain size distribution. Temperature control is one of the important conditions for the reduction of the impact of tungsten powder, good temperature control and promoting the reduction rate, conducive to the completion of the crystalline tungsten powder and tungsten can effectively eliminate the defects of structure inside. If the reduction temperature is too high, tungsten powder will agglomerate, tungsten powder granularity distribution widened, which will also widen the distribution of WC powder granularity.

Tungsten copper contact has excellent electrical, thermal conductivity and chemical stability, but the problem in densification is always a barrier in its developing way. And this incomplete densification will have an bad influence on the hardness, the strength, wear resistance and arc ablation resistance conversely. So the relevant researchers propose that pressure sintering, a total reduction of chemical and explosive compaction method special process to improve the density of tungsten copper contact material. However, there are some defects in these processes, such as high operation and maintenance costs, be suitable for the parts with small size and so on.

In order to improve the properties of tungsten copper contacts, we combine tungsten copper contact used in high voltage circuit breakers to study HIP process for tungsten copper material impact, and its elimination of the porosity, densification mechanism and related factors. HIP (Hot Isostatic Pressing), it places the product into a closed container, which is applied to each peer pressure while applying heat, under the action of high temperature and pressure, the product can be sintered and densified. HIP has many advantages, such as combines the advantages of hot pressing with isostatic pressing, lower molding temperature, excellent densification and performance, which is essential for high-performance material manufacturing; now, in the United States, Japan and Europe to achieve the industrial, marine, aviation, aerospace, automotive and other fields have been widely used.