Study on grinding deformation of Al2O3-TiC slender bar
The deformation of brittle and hard material slender bar has great significance in contour grinding process. In this paper, the grinding deformation for Al2O3-TiC slender bar was studied. Diamond lapping film and adhesive mounting method were applied in the experiments. The influences of grinding pressure, grinding speed and stress on deformation were discussed in detail based on the theoretical analysis and the measurement of straightness in different conditions. The bend deformation goes up with the increase of grinding pressure and speed. The internal stress will bring large deformation after grinding. Releasing the stress will improve the deformation. Experiments shown that releasing the stress two-thirds at a proper condition before final grinding can achieve the deformation below 1000nm. Employing lapping film and adhesive mounting method in optimal condition, the Al2O3-TiC slender bar deformation in grinding can be controlled.
Warp in High Precision Cut-Off Grinding of Al2O3-TiC Ceramic Thin Plate
Abstract High precision cut-off grinding has been carried out on Al 2 O 3 -TiC ceramic thin plates with metal bond thin diamond wheels. The warp of the cut-part as well as the flatness of work surface, i.e. deflection of wheel, was precisely measured and thus, the warp generation mechanism was analyzed and the optimum slicing condition was investigated. Grinding forces were measured for discussing the warp. Also, the effect of V-shaped guide groove for depressing the deflection was studied. It is evident that the warp of workpiece and the wheel deflection largely depend on grinding type and pre-processing conditions. The high feed cut-off grinding is most effective for restraining the deflection, and the use of a V-shaped groove is a useful way to depress the deflection
Experimental investigation of the geotechnical properties and microstructure of lime-stabilized saline soils under freeze-thaw cycling
Abstract The Song-Nen Plain in northeastern China holds one of the three largest expanses of soda saline-alkali soil in the world. Due to its disadvantageous geotechnical properties, the saline soil in this area is unable to meet the needs of construction projects. This study evaluates the stabilizing effect of adding lime to such soils. Specifically, it investigates how the physicochemical and mechanical properties and microstructure of soda saline-alkali soil are altered by lime and how these changes are affected by both freeze-thaw cycling and the duration of curing. The results reveal that adding lime to saline soil transforms clay particles into sand and silt particles and causes the pore size distribution (PSD) to become bimodal, with small-pore and macropore populations. An increase in lime content leads to an increase in the unconfined compressive strength (UCS) but a gradual decrease in both the cation exchange capacity (CEC) and plastic index. Freeze-thaw cycles break up coarse particles and aggregate finer particles, increasing the diameter of macropores and decreasing the USC; however, the effect on specimens with >9% lime is negligible. It is further shown that the geotechnical properties of the soil change immediately after the addition of lime, indicating that the cation exchange reaction takes place very quickly. Furthermore, the pozzolanic reaction leads to an increase in the percentage of sand-sized particles and a decrease in porosity after 28 days of curing. Overall, these results indicate that it is feasible to use lime to improve the engineering properties of soda saline-alkali soil in this area.