Study On Two-sided Lapping And Polishing Characteristic Of The BaTiO₃ Ceramics Substrate

Barium titanate(BaTiO3) is one of the most common perovskite ferroelectric materials,which is widely used in military, atomic energy, aerospace, metal, oil, chemical industry, daily household appliances and so on because of its excellent piezoelectric properties, high dielectric constant, low dielectric loss and high voltage resistance. The BaTiO3 ceramics substrates are prepared by the sintered processing, and the surface is not flat and the thickness also is not in conformity with the requirements. Meanwhile the barium titanate ceramics is a soft brittle material, which makes the processing very difficulty and costly. The lapping and polishing processing are the efficient ways to make the barium titanate ceramic meet the requirements, so using an appropriate processing technology is the key to efficient processing. So this study is focused on barium titanate ceramics substrate.The mechanism of material removal, lapping trajectory, mechanical properties of materials as well as the lapping and polishing process were studied. The main work of the research is as following:1. Introduces the principle of two-sided lapping, and analyses the processing mechanism of the lapping process and the form of material removal mechanism.2. Derives the movement track equation of abrasive relative to the workpiece in the the UN1POL-160D two-sided lapping and polishing machine, then make a trajectory simulation using a Matlab program, and analyze the influence of various factors on the trajectory; Then the trajectory of multiple particles was simulated, and the influence of the rotation speed of the lapping pad, the lapping time and the abrasive distribution on the trajectory and the lapping effect were researched.3. Using the Nano Indenter G200 to do nanoindentation experiments on the barium titanate ceramics substrate, and the elastic modulus E, the hardness H and the fracture toughness Kc are obtained. The critical cut depth of the brittle-ductile transition was achived by the Bifano model.4. BaTiO3 ceramic substrate was machined by two-sided lapping and the influence of the rotation speed of the lapping pad, lapping pressure, the variety of abrasive, the abrasive particle size, the fluid flow and the concentration of fluid on the surface roughness (Ra) and material removal rate (MRR) were studied. A set of efficient barium titanate ceramic substrate two-sided lapping process was obtained by optimizing the process parameters. After polishing, a super smooth surface with surface roughness Rα 6 nm was achieved.