ANALYSIS OF HYDRODYNAMICS IN THE SYNTHESIS OF CRYSTALS FROM WATER-SALT SOLUTIONS

In application to KDP crystal growth on a functioning crystallizer, the local features of solution hydrodynamics near the growing crystal surface, which may affect on the crystallographic conditions of crystal growth and the defect formation, are established by mathematical modeling. The design of a modernized crystallizer, which provides an axisymmetric flow around of a growing crystal by a water-salt solution, is considered.

Interaction Mechanism of Thermal and Mechanical Field in KDP Fly-Cutting Process

As an important nonlinear optical material, potassium dihydrogen phosphate (KDP) crystal is used in high-power laser beams as the core element of inertial confinement fusion. It is the most general method of single point diamond fly-cutting (SPDF) to produce high precision and crack-free KDP surfaces. Nevertheless, the cutting mechanism of such material remains unclear, and therefore needs further analysis. Firstly, the stress field, cutting force and cutting temperature under different working conditions are calculated by a KDP crystal cutting simulation model. Then, the rules and the cause of change and interaction mechanisms of force and temperature are analyzed by comparing the measurement experiments with simulations. Furthermore, the causes of chip formation and micro-cracks on the machined surface are analyzed based on thermo-mechanical coupling and chip morphology. The conclusion can be deduced: Although the temperature has not reached the phase transition temperature during the finishing process, under high cutting speeds and large unformed chip thickness, such as semi-finishing and roughing, the temperature can reach up to 180 °C or higher, and KDP crystals are very likely to phase transition—chip morphology also verifies this phenomenon.

A two-parameter model for predicting thermal contact resistance between crystal and aluminum alloy based on turning morphology

Thermal contact resistance (TCR) is a key factor in thermal engineering which affects the thermal-structural design of precision instruments. To reveal the influence of turning morphology on the TCR between potassium dihydrogen phosphate (KDP) crystal and aluminum alloy, a novel simplified model considering two parameters of wavelength and slope is proposed. Meanwhile, the TCR of KDP crystal and aluminum alloy are experimentally investigated to validate this two-parameter model, where the effects of different wavelengths and slopes on Mises stress distribution, temperature distribution, heat flux and TCR can be analyzed. By incorporating the theory of plane turning, the TCR can be reduced by controlling the feed rate and cutting thickness under a certain roughness. This research provides a theoretical basis for the thermal-structural design of crystal modules and the turning of aluminum alloy.