Sintering of tungsten carbide particles sputter-deposited with stainless steel

The purpose of this work was to study the sintering process of WC-stainless steel AISI 304 composite powders prepared by an innovative process, which consists in the use of a magnetron sputtering to coat WC powder particles with the stainless steel elements. The sintering of pressed compacts was performed in a conventional vacuum furnace using a heating rate of 5degreesC min(-1) until the selected maximum temperature, a holding time of 50-173 min and a sintering pressure of 2-20 Pa. For comparison, a conventional prepared WC powder with 6.5 wt.% of stainless steel AISI 304 was also studied. During the sintering of the coated powders, three different sintering stages were identified: an initial one due to solid state matter transport until similar to1150degreesC, followed by two other stages where liquid phase may be already present. Very high weight losses occurred during the sintering of coated powder which was diminished by the shortening of the holding time, the increase of the pressure in the sintering furnace and the appropriate control of the sintering atmosphere. Despite the high values of weight loss, 96% of densification can be obtained at a relatively low sintering temperature, T = 1325degreesC, for an initial content of similar to10 wt.% of binder phase. (C) 2003 Elsevier Ltd. All rights reserved.