This invention discloses a cooling liquid for ultraprecision milling of functional potassium dihydrogen phosphate crystals. Since potassium dihydrogen phosphate crystals have such characeristics as easy deliquescence, high softness, high brittleness, high temperature-change sensitivity and easy cracking, traditional cooling liquids may cause surface fogging phenomenon or even surface cracking. The cooling liquid in this invention is composed of: aviation kerosene as the matrix, EDTA 1.598-3.2 mg/L and sulfosalicylic acid 0.031-0.1 mg/L. The cooling liquid can largely reduce surface roughness of processed crystals, lower surface residual stress, inhibit surface fragile damage and avoid surface fogging phenomenon. |