Joining interface and grain fracture of single-layer brazed grinding wheels with binderless CBN grains

摘要

Fabrication experiments of single-layer brazed grinding wheels were carried out using binderless cubic boron nitride (CBN) grains, Cu-Sn-Ti alloy and AISI 1045 steel. The brazing temperature was 900℃ and the dwelling time was 8 min. The microstructure of the joining interface was characterized. The performance of the grinding wheels was evaluated during high-speed grinding nickel superalloy. The fracture behavior of the abrasive grains versus the embedding depth was studied quantificationally. Results obtained show that good joining interface were formed among binderless CBN grains, Cu-Sn-Ti alloy and AISI 1045 steel dependent on the elemental diffusion and chemical reaction during brazing, which ensures firm hold to the abrasive grains. The grinding wheel with binderless CBN grains has exhibited evident advantages upon that with monocrystalline CBN grains in terms of grinding force and force ratio. The critical force acting on the binderless CBN grain with the exposing height of 50 and 70% is determined when the grain fracture takes place.