▎ 摘　　要

NOVELTY - Preparation of powder metallurgy friction materials involves using silicate solution to prepare nano-silica, fully grinding, sieving, obtaining nano-silica powder, using modified Hummer method to process graphite, preparing graphene oxide, crushing, sieving, placing nano-silica powder and graphene oxide powder in reactor, adding deionized water, shaking, obtaining a uniformly dispersed graphene oxide and nano-silica mixed suspension, using a surface modification to prepare a graphene-nano-silica hybrid material using a uniformly dispersed graphene oxide and nano-silica mixed suspension, mixing with copper powder and silicon carbide powder, ball milling, obtaining mixture (A), mixing with iron powder, heating, obtaining mixture (B), mixing with zirconia powder and molybdenum disulfide powder, adding kerosene, stirring, obtaining mixture (C), compressing, obtaining compact, pressurizing, sintering, fixing on supporting steel back, sintering, and cooling. USE - Preparation of powder metallurgy friction materials (claimed). ADVANTAGE - The method provides powder metallurgy friction materials with excellent physical and mechanical properties, and stable friction and wear properties. The powder metallurgy friction materials have high friction coefficient, small friction coefficient changes with temperature, pressure and speed, high temperature resistance, small abrasion and long service life when compared with existing asbestos resin or metal friction materials. DETAILED DESCRIPTION - Preparation of powder metallurgy friction materials involves (1) using silicate solution to prepare nano-silica, fully grinding nano-silica, sieving, obtaining nano-silica powder, weighing powder metallurgy friction material raw materials comprising 30-40 parts mass powdered raw material copper, 20-30 parts mass iron, 12-20 parts mass nano-silica, 8-15 parts mass zirconia, 6-12 parts mass molybdenum disulfide, 5-7 parts mass silicon carbide and 3-5 parts mass graphite, (2) using modified Hummer method to process graphite for preparation of graphene oxide, crushing the prepared graphite oxide, sieving, obtaining graphene oxide powder with a particle size of less than 0.1 mm, placing nano-silica powder and graphene oxide powder in a reactor, adding deionized water to the reactor, shaking the reactor, ultrasonically dispersing at 50-55 kHz for 8-20 minutes, obtaining a uniformly dispersed graphene oxide and nano-silica mixed suspension, (3) using a surface modification method to prepare a graphene-nano-silica hybrid material using a uniformly dispersed graphene oxide and nano-silica mixed suspension, mixing the graphene-nano-silica hybrid material with copper powder and silicon carbide powder, stirring, placing in a ball milling device for ball milling, obtaining mixture (A), (4) mixing the mixture (A) with iron powder, placing in the reactor, heating to 30 degrees C at a heating rate of 30 degrees C/minute for 20-30 minutes, heating to 450 degrees C at a rate of 50 degrees C/minute for 1-2 hours, cooling at 100 degrees C/minute for rapid cooling until the temperature in the reactor drops to room temperature, opening the reactor, taking out the product, obtaining mixture (B), (5) mixing zirconia powder and molybdenum disulfide powder with the mixture (B), placing in the passing mixer, adding kerosene to the mixer, stirring at 40-80 rpm for 30-50 minutes, stirring until the kerosene and solid matter are completely fused, obtaining mixture (C), (6) compressing the mixture (C), using compression molding, feeding the mixture (C) under 400-600 MPa environment and hold pressure for 3-5 minutes for compression molding, obtaining compact, pressurizing the compact, sintering at a high temperature in a reducing atmosphere or an inert atmosphere, metallurgical bonding with the supporting steel back, fixing on the supporting steel back, fixing the compact on the supporting steel back, placing in a reducing atmosphere or an inert atmosphere under the condition of 3-6 MPa, sintering at a temperature of room temperature to 820-950 degrees C and pressure of 2-4 MPa for 3-5 hours, and cooling. An INDEPENDENT CLAIM is included for powder metallurgy friction material prepared by the method, which comprises 30-40 parts mass copper, 20-30 parts mass iron, 12-20 parts mass nano-silica, 8-15 parts mass zirconia, 6-12 parts mass molybdenum disulfide, 5-7 parts mass silicon carbide, and 3-5 parts mass graphite.