Preparation method of nanoscale SiC powder with controllable macro particle size

The invention relates to a preparation method of nanoscale SiC powder with controllable macro particle size, which comprises the following steps: (1) weighing reaction materials according to a preset proportion, and adding an inert diluent with a preset content to prepare an initial mixture; (2) uniformly mixing the initial mixture in a ball mill, and then pressing into a cake-shaped blank with the diameter of 80 mm and the height of about 20-50 mm on a press machine; (3) putting the cake-shaped blank into a reaction kettle, putting an ignition agent on a blank body, filling protective gas for gas washing, then filling the protective gas for pressure maintaining, and continuously heating until a self-propagating reaction occurs in a system, so as to obtain a black blocky initial product; and (4) crushing the primary product, leaching with a hydrochloric acid solution and distilled water, and drying in a vacuum drying oven after the purification standard is reached, thereby obtaining the nano SiC powder with c