Tungsten Copper Machining

The melting point of tungsten, copper vary greatly higher than the boiling point of the copper melting point of tungsten and tungsten copper immiscible, the general method of smelting is difficult to produce tungsten copper alloy, the only powder metallurgy to make tungsten copper composites manufacturing to become a reality. The method of preparation is mainly divided into two categories: infiltration and direct sintering method. In recent years, due to the rapid development of nanotechnology, directly obtained by sintering a great development.

Infiltrated divided into high temperature sintered tungsten skeleton copper infiltration and low-temperature sintering mixed powder copper infiltration two.

W powder +0.1% to 0.5% binder - compaction - removal of the binder - reinterred - high temperature sintering - copper infiltration, this method can be obtained relative density> 99.2% tungsten copper materials. As a result of the high temperature sintering, W restore very good, low melting point impurities difficult to restore sub oxide can be removed by volatilization and thermal decomposition. The oxygen content of the tungsten and copper material is very low, high purity, high temperature sintering method suitable for manufacture of the mass fraction of copper is not greater than 15% of the tungsten and copper material. The use of high-temperature sintering method of manufacturing the material relatively high density, good overall performance. The only drawback is the high temperature sintered tungsten skeleton Production cycle is long and complex, and higher production costs.

Part of the mixed powder sintering process copper infiltration method generally has the following two:
Cu powder and 0.5% to 2.5% additives (typically nickel powder) - press molding - sintering - copper infiltration.
The process is simple; this method is suitable for manufacturing Cu> 20% tungsten-copper composite. Various methods to the production of tungsten copper materials, copper distribution along the tungsten grain boundaries, the tungsten skeleton strength is not as good as the high-temperature sintering method, as this method of asking too much of raw materials, ingredients, or the product will contain more impurities and gases.
BW powder - +2.5% Cu powder + static acid - was added to the appropriate melt composite adhesive agent (containing 35% polypropylene, 60% paraffin wax, 5% satiric acid) - the cooling granulation injection form - binder removal - heptanes - 3C% / min heating to 500C, 10C/min heating to 900C - transferred to the high-temperature sintering furnace cooling - heating 10C/min to 1030C - to 10C/min heated to 1200-16200C Melting leaching - cooled to room temperature.

The name suggests, a direct sintering method, after forming the desired composition of the mixed powder of tungsten and copper repression directly sintered product. Depending on the mixed powder preparation method used, mainly mixed oxide, restore law and mechanical alloying process; powder particle size and mechanical alloy powder is divided into general mechanical alloying powder and mechanical alloying nano powder; addition there, the liquid phase activated sintering method. Previously obtained in this process after sintering of copper tungsten material density is low (relative density of less than 97%), especially Cu is less than 15%, the material is more severe, and thus generally can not be applied directly. In recent years, due to the method of flour milling and powder pretreatment methods to improve, it is possible to obtain a high density sintered product (relative density greater than 99%), and the widespread concern and a rapid development.