Grinding Performance Integrated Experimental Evaluation on Alumina Ceramics with Leaf-Vein Bionic Grinding Wheel

In order to enhance the grinding performance of alumina ceramic materials, the surface of the grinding wheels are ablated by laser radiation before grinding, and the three types of leaf-vein bionic grinding wheels with different micro-groove pitches are formed to compare the grinding experiments with normal grinding wheels. The grinding forces and surface roughness were gauged and the morphological characteristics of ground workpiece surfaces were studied. The results showed that with the increase of groove pitch, the normal grinding force was reduced by 9.6-63%, while the tangential grinding force is reduced by 8.3-42%. The groove can promote the flow of coolant, accelerate the heat dissipation and chip removal in the grinding area, reduce the damage of the workpiece and the wear of the grinding wheel, so the vein bionic grinding wheel had more tremendous processing advantages. Among the four kinds of grinding wheels, the leaf-vein bionic grinding wheel with groove pitch equal to 8mm obtained the best grinding effect. The vein-shaped groove had a positive impact on the grinding process.

Tribological Behaviour of Alumina Ceramics with Nano TiO2 as a sintering aid in Non-Conformal Contact

The study emphasized the sintering behaviour and tribo-mechanical properties of alumina ceramics by nano TiO2 addition as a sintering aid. With increase in sintering temperature, the bulk density of alumina has increased gradually and optimized at 1600°C. The optimizing effect of densification at 1600°C is 98.25% by the addition of 1 wt.% nano TiO2. The maximum solid solubility of titania in alumina grains was at 1600°C, causes optimisation of densification by 1 wt. % addition. The excess addition of TiO2 formed low dense Al2TiO5, appear as a secondary phase at grain boundaries and does not significantly improved densification. Fracture toughness increases and coefficient of friction decreases with the addition of nano TiO2 in alumina matrix. The 1wt.% nano TiO2 addition improved hardness to 8.82% and reduces specific wear rate to 45.56%. The 1wt.% nano TiO2 addition greatly influenced the microstructure of sintered Al2O3. The morphology was sharply changed from hexagonal columnar shape to order sub round orientation which also directly impact the tribo-mechanical properties of sintered alumina. The 1wt.% addition substantially decreases wear track depth as observed by 3D surface profilometer. Microscopic observation of the worn-out surface showed that wearing is majorly caused by plastic deformation and abrasion.

Evaluation of magnetic properties of thin magneto-dielectric films deposited from beam plasma in medium vacuum

By electron-beam evaporation of a solid state dielectrics (alumina ceramics) and a magnetic material (steel-3) in fore-vacuum, thin films of several μm, possessing both dielectric and magnetic properties, were deposited on a substrate. The work shows that the microstrip resonator method can be used to assess the presence of magnetic properties in films.