Magnetic composite fluid optimization for KDP crystal polishing based on a D-optimal mixture design

Area of Science:

• Materials Science
• Optics
• Surface Engineering

Background:

• Potassium dihydrogen phosphate (KDP) crystals are crucial electro-optical nonlinear optical materials with broad applications.
• Existing KDP processing techniques have limitations, and polishing with magnetic composite fluid (MCF) has not been previously explored.

Purpose of the Study:

• To develop a non-water-based MCF suitable for polishing water-sensitive KDP crystals.
• To optimize the MCF composition and processing parameters for KDP surface finishing.
• To establish a mathematical model correlating MCF components with surface roughness.

Main Methods:

• A non-water-based MCF was formulated considering KDP's water solubility.
• Orthogonal experiments were conducted to determine optimal MCF processing parameters.
• A D-optimal mixture design was employed to optimize the MCF component ratios and model surface roughness.

Main Results:

• The optimal MCF composition was determined as 20 wt.% base liquid, 39.962 wt.% carbonyl iron particles, and 25.038 wt.% Fe3O4.
• Polishing KDP with the optimized MCF for 60 minutes resulted in a surface roughness (Ra) of 7.5 nm.
• The achieved surface roughness was consistent with theoretical predictions, validating the optimization method.

Conclusions:

• The developed non-water-based MCF is effective for polishing KDP crystals.
• The optimization strategy using orthogonal and D-optimal designs provides a reliable method for formulating MCFs.
• This research offers a promising new technique for high-performance KDP crystal surface finishing.