Study of the effect of alumina percentage in WC-Ni-Al2O3 composite powder processed via High Energy Milling (HEM)

ABSTRACT

The PM consists of at least three stages: obtaining the powder, consolidation and sintering. In the stage of obtaining the powders, a widely used technique is the High Energy Ball Milling (HEM) which, besides providing the breakdown of the pre-existing particles, can also improve the dispersion of the components. A material obtained by the technique is WC-Co, the hard metal, which despite having interesting properties, such as, for example, high hardness and resistance to compression, cannot maintain such characteristics when put to work in the presence of high temperatures, such as cutting in machining. As an alternative to the WC-Co composite system, the replacement of cobalt by nickel is studied, however, the WC-Ni composite has a low hardness when compared to the WC-Co. To minimize this effect, the present study investigated the possibility of adding aluminum oxide (Al₂O₃) to WC and Ni powders. The study established the influence of high energy ball milling (MAE) on the characteristics of the composite powders WC-Ni-Al₂O₃ with 5 and 10% w of Al₂O₃. HEBM (400 rpm) was carried out in a wet way, and samples were taken at 1, 2, 4, 10 and 20h. The samples were characterized by: XRD, laser granulometry and SEM / EDS. The results were promising since there was a reduction of up to 50% in the median particle size with the studied times, as well as the formation of composite particles.

Keywords
Composite particles; High energy ball milling; Cutting tool