Tungsten Carbide Grain Shape/Size Friend or Foe
Shape of the Tungsten Carbide Crystal yieds application value.The ball is the strongest geometric shape.A sharp edge provides the ability to cut and shear.Spacing between shapes provides value to the surface.Tungsten carbide is virtually billions of tungsten carbide(WC) shapes suspended in a matrix.The matrix is generally a pure metallic material,like cobalt (Co),Nickel(Ni),Chrome(Cr)oriron(Fe).The matrix can be a mixture of metals,like Co mixed with Ni.In this case of Co and Ni,a harder more joinable matrix results.The(WC)grain is measured in microns(um).The smallest grain commercially produced is 0.5um and the largest is 25um.A micron is 0.0000039" or equal to the human hair being divided 100 times.Grain size of(WC) is determined by the carburization process and milling(grinding)process.The grain size cann't be measured by typical screening or other mechanical processes.It is determined microscopically.Grain sizes are measured microscopically on an average basis.When a(WC)grain is specified,it is specified by the largest percent present in the mixture of grains.Typically,2um~3um grain size will have 25% crystals below 2um~3um and 25% above 2um~3um.This means even though the average is 2um~3um,it will have fines as low as 0.5um and macro grains as high as 25um.
Virgin WC crystals will have sharp corners,depending on the average grain size and the length of time the WC powder was milled.Sharp corner are good for cutting.Rounded edges are good for wearing.
