Polypropylene composite material with low linear expansion coefficient and high surface hardness and preparation method thereof

The invention relates to a polypropylene composite material with low linear expansion coefficient and high surface hardness, which comprises the following components by weight: 100 parts of PP resin, 5 to 15 parts of functional fused silica powder, 10 to 20 parts of functional wollastonite powder, 8 to 15 parts of POE, and 0.3 to 0.5 part of an antioxidant. The functional wollastonite powder is a product obtained after wollastonite is subjected to surface treatment by an ultra-dispersion coupling agent, and the weight part ratio of the wollastonite to the ultra-dispersion coupling agent is (20: 1)-(25: 1); the functional fused silica powder is a product obtained after surface treatment is carried out on fused silica through an ultra-dispersion coupling agent, and the weight part ratio of the fused silica to the ultra-dispersion coupling agent is 25: 1-30: 1; the linear expansion coefficient of the fused silica is 0.5 * 10 mm/mm/DEG C; the ultra-dispersion coupling agent is a coupling agent SP-1013 produce