Influence Of Grain Size And Crystal Type On The Mechanical Properties And Sputtering Resistance Of BN Ceramics

h-BN powders was ball milled to be sub-microned, and the hot-pressing sintering time and temperature was controlled to get different grain sizes of ceramic.h-BN and c-BN powders and fused quartz were hot-pressing sintered, to prepare the h-BN/Si O2 and c-BN/Si O2 composite materials.Using the XRD, SEM to characterize the phase and microstructure of materials; universal testing machine was used to study h-BN ceramic mechanical properties;byionerosion experiments, studied the h-BN ceramic ion sputtering resistance, analysed the after erosion phase on the surface of the material, roughness and microstructure characteristics, and has carried on the exploration to the sputtering mechanism of the material.Studies have shown that under the condition of the same time, with the improvement of hot pressing sintering temperature, h-BN ceramic grain size increases gradually, when theholding time is 0.5h, temperature increase from 1600 oC to 1900 oC, the grain size increase from 0.5μm to 8μm. h-BN ceramic grain size also increase with the holding time, when the temperature is 1800 oC, the holding time increased from 1h to 5h, the grain size increase from 4μm to 8μm.With the increase of h-BN ceramic grain size, the bending strength decrease, and the relationship between bending strength and grain size conform to the Hall-petch formula.The h-BN ceramic with the grain size of 0.5μm has the best elastic modulus, bending strength and fracture toughness, as 50.1 GPa, 163.5 MPa and 2.85 MPa×m1/2.Theion sputtering resistance properties of h-BN ceramic material gradually decreased with the increase of grain size, surface roughness and the sputtering rate gradually increased with the increase of the grain size.The erosion rate increase with the ion energy, while decrease with the erosion time.h-BN and c-BN were used respectively and fused quartz as raw materials, were hot pressied to different crystal forms of BN/Si O2 composite materials. With the increase of sputtering ion energy, sputtering rate increase gradually. Under the condition of the same ion energy, when the sputtering time increase, sputtering rate gradually decreased;h-BN grain in BN/Si O2 composite material was more easily than fused quartz and cristobalite sputtered, and c-BN/Si O2 composite materials was sputterred, fused quartz coated h-BN grain is sputterred first, and then c-BN grain due to debonding and separation with fused quartz substrate, thereby causing mess loss to the whole materials.