Morphology investigation of removal particles during laser cutting of Al^sub 2^O^sub 3^ ceramics based on vapor-to-melt ratio

An investigation of particle morphology based on vapor-to-melt ratio is carried out to reflect the relationship between the forms of material removal and effects of cutting process. The influences of vapor-to-melt ratio on morphology of removal particles (average diameter, diameter distribution, sphericity, spheroidization rate and density distribution) is investigated by the experimental observation and analysis. It is shown that, a steady processing state with maximum average diameter, concentrated distribution, better sphericity, lager spheroidization rate and higher hollow proportion of removal particles is obtained at a relatively large value of vapor-to-melt ratio. However, at a too high value of vapor-to-melt ratio, a small quantity of material breaks and strips in a substrate form by the hot tearing effect of material. These irregular residues are mixed in the total removal collection, thereby reducing the average sphericity of the overall removal. When the particle diameter is greater than 100 μm, a complete cavity is formed close to the center, and the diameter is about 1/2 that of the whole particle.