Nickel-coated hexagonal boron nitride nanosheet composite powder, preparation and high performance composite ceramic cutting tool material

A method for preparing a nickel-coated hexagonal boron nitride nanosheet composite powder (BNNS@Ni) comprising the following steps:

• (1) adding BNNS powder into isopropanol, ultrasonically dispersing for 20-30 min, and then centrifugally separatinge to obtain dispersed BNNS powder;
• (2) adding the dispersed BNNS powder into a sensitizing solution, ultrasonically oscillating and stirring for 10-15 min, centrifugally separating after tin particles in a sensitizing solution are filtered out, and washing once with distilled water to obtain sensitized BNNS powder;
• wherein the sensitizing solution comprises:
• 10-15 g/L of stannous chloride dihydrate, the balance is isopropanol, and 3-5 g/L of tin particles are added;
• (3) the sensitized BNNS powder obtained in step (2) is added into an activating solution, ultrasonically oscillated and stirred for 10-20 min, centrifugally separated and washed to neutrality with distilled water to obtain activated BNNS powder;
• then it is added into a PVP solution, ultrasonically oscillated and stirred for 5-10 min to prepare an activated BNNS suspension, which is sealed for later use;
• the components of the activating solution are:
• 0.2-0.5 g/L of palladium chloride (PdCl2), 5-10 mL/L of concentrated hydrochloric acid, 5-10 mg/L of polyvinylpyrrolidone (PVP), and the balance is distilled water;
• (4) electroless plating solution is prepared, and the components of the electroless plating solution are:
• 15-25 g/L of nickel sulfate hexahydrate, 50-60 g/L of ethylenediamine tetraacetic acid disodium dihydrate, 40-50 g/L of ammonium sulfate, 15-25 mL/L of a first dose of hydrazine hydrate, 5-10 mg/L of polyvinylpyrrolidone, 0.2-0.5 mg/L of potassium iodide, a pH adjuster that makes the pH value of the electroless plating solution at 10-11, and the balance is distilled water;
• in addition, 15-25 mL/L of a second dose of equal amount of hydrazine hydrate is prepared for later use;
• the activated BNNS suspension obtained in step (3) is added into the prepared electroless plating solution;
• first, the plating is carried out for 5-10 min in a constant temperature water bath at 85-90° C. and under ultrasonic oscillation condition, then the second dose of hydrazine hydrate is added dropwise under stirring condition;
• afterwards the plating is carried out in a constant temperature water bath at 50-60° C. and under ultrasonic oscillation condition, and the pH adjuster is dripped at any time to keep the pH value of the electroless plating solution at 10-11;
• (5) after the plating in step (4) is completed, the solid particles are centrifugally separated and washed to neutrality with distilled water, then washed with absolute ethanol for 2-3 times, and dried in a vacuum drying oven at 30-40° C. for 10-15 h to obtain nickel-coated hexagonal boron nitride nanosheet composite powder.