Effect of Wetting Characteristics of Polishing Fluid on the Quality of Water-Dissolution Polishing of KDP Crystals

Abstract

KDP crystals constitute the only laser-frequency conversion and electro-optical switches that can be used in laser systems for inertial confinement fusion. However, KDP crystals are difficult to produce because of their inherent softness, brittleness, water-solubility, and temperature sensitivity. The authors’ group developed a water-dissolution polishing method in previous studies to obtain near-damage-free KDP surfaces. In this article, the effect of the wetting characteristics of the water dissolution polishing fluid on the crystal surface—a factor rarely considered in the usual process optimization—on the polished surface quality was comprehensively studied. The mean radius of micro water droplets at 5 wt.% and 7.5 wt.% water content was approximately 0.6 nm and 1.2 nm, respectively. Theoretically, the smaller micro water droplet size is beneficial to the polished surface quality. When the water content was 5 wt.%, due to the poor wetting characteristics of the polishing fluid, surface scratches appeared on the polished surface; when the water content was 7.5 wt.%, the effects of the wetting characteristics and the radius of the micro water droplets reached a balance, and the polished surface quality was the best (Ra 1.260 nm). These results confirm that the wetting characteristics of the polishing fluid constitute one of the key factors that must be considered. This study proves that the wetting characteristics of the polishing fluid should be improved during the optimization process of polishing fluid composition when using oil-based polishing fluids for ultra-precision polishing.

Influence of Ca-substituted K-induced cluster defects on the electronic structure and optical properties of KDP crystals

“…Such attributes make it highly desirable for applications related to inertial confinement fusion (ICF). However, the actual resistance to laser damage falls short of the theoretical value, primarily due to intrinsic defects within the crystal or defects introduced during the growth process [4][5][6] .…”

Effects of pH Values and H2O2 Concentrations on the Chemical Enhanced Shear Dilatancy Polishing of Tungsten

“…The surface quality of tungsten film will affect the interconnect performance of devices, and therefore the surface of tungsten film needs to be polished [ 8 ]. Ultra-precision polishing is the final processing method to reduce the surface roughness of workpiece, remove the damaged layer, and obtain high surface accuracy and excellent surface quality [ 9 , 10 , 11 ]. However, as a typical hard and brittle material, there are great challenges in the ultra-precision polishing of tungsten due to the high hardness, high brittleness, and great wear resistance of material [ 12 , 13 ].…”

Editorial for the Special Issue on Advanced Manufacturing Technology and Systems

“…A mechanism for the micro removal of materials in the UEVC process was obtained. Wang et al [ 9 ] developed a water-dissolution polishing method to obtain near-damage-free KDP surfaces. They proved that the wetting characteristics of the polishing fluid should be improved during the optimization process of polishing fluid composition when using oil-based polishing fluids.…”