▎ 摘　　要

NOVELTY - Preparation of graphene oxide composite magnesium-based laminated gradient material involves adding 0.13 g graphene oxide to 500 ml deionized water, ultrasonically processing using ultrasonic device for 2 hours to prepare graphene oxide suspension, adding 42.5 g magnesium alloy powder to the graphene oxide suspension, mechanically stirring at 300 rpm for 2 hours, filtering and drying to obtain mixed powder (A) containing 0.3 %mass graphene oxide, weighing mixed powder (A) into five portions, separately mixing each portion of mixed powder (A) and boron carbide powder respectively by ball milling process to prepare mixed powders (B) containing boron carbide, sintering the mixed powder (B) at 480degrees Celsius to form single-layer materials containing boron carbide, cleaning graphite mold, placing single-layer material containing 25 %mass boron carbide into graphite mold, evenly spreading magnesium alloy powder layer on the upper surface of the single-layer material, and sintering. USE - Preparation of graphene oxide composite magnesium-based laminated gradient material for preparing non-ferrous metal composite materials and automotive application, aerospace applications and 3C product. ADVANTAGE - The prepared composite material has excellent structure compactness and refined grain size. DETAILED DESCRIPTION - Preparation of graphene oxide composite magnesium-based laminated gradient material involves adding 0.13 g graphene oxide to 500 ml deionized water, ultrasonically processing at power of 720 W using ultrasonic device for 2 hours to prepare graphene oxide suspension, adding 42.5 g magnesium alloy powder, mechanically stirring at 300 rpm for 2 hours, filtering and drying to obtain mixed powder (A) containing 0.3 %mass graphene oxide, weighing mixed powder (A) into five portions such as 9.5 g, 9 g, 8.5 g, 8 g and 7.5 g, separately mixing each portion of mixed powder (A) and 0.5 g, 1 g, 1.5 g, 2 g, and 2.5 g of boron carbide powder respectively by ball milling to prepare mixed powders (B) containing boron carbide in an amount of 5 %mass, 10 %mass, 15 %mass, 20 %mass and 25 %mass, sintering mixed powder (B) at 480degrees Celsius to form single-layer materials containing boron carbide in an amount of 5 %mass, 10 %mass, 15 %mass, 20 %mass and 25 %mass by cleaning inside of the graphite mold with metal shovel and metal brush, then cleaning inner surface of mold with absolute ethanol, adding mixed powder (B) into graphite mold, covering graphite mold with thermal insulation carbon felt, putting graphite mold into the graphite board in furnace, turning on power, turning on the axial pressure device, adjusting initial pressure of indenter to 10 MPa, lowering indenter to secure the graphite mold and make the thermocouple hole on the graphite mold and the infrared meter hole and the thermocouple hole of the sintering furnace component and infrared meter hole on the same horizontal line, and then closing the furnace door and vacuum valve, starting the vacuum pump, opening the vacuum valve connected to the sintering furnace component after the vacuum pump is running normally, vacuumizing the sintering furnace to 10 Pa, closing the vacuum valve, opening pressure valve, passing argon gas to sintering furnace until the pressure balance between the inside and outside of the sintering furnace, opening water inlet valve and setting the water inlet volume to 0.2-0.3 MPa after confirming that the water path is unobstructed, closing the water inlet valve and turning on the power air switch of the water pump to pump the cooling water back, setting heating rate to 80degrees Celsius/minute, starting the hydraulic pump to increase the head pressure to 20 MPa, and maintaining the pressure until the end of the temperature rise, setting sintering time for 20 minutes when the temperature rises to the set temperature, so that thermocouple monitors the temperature in the furnace in real time, direct current pulse power sinters the mixed powder (B), increasing hydraulic pump head pressure to 50 MPa , and maintaining the pressure until the end of sintering, water cooling when the temperature of the sintering furnace reaches room temperature, opening the furnace door of the sintering furnace, taking out and opening the graphite mold, demolding and taking out the single layer material, cleaning the graphite mold, placing single-layer material containing 25 %mass boron carbide into graphite mold, evenly spreading magnesium alloy powder layer (A) with thickness of 1-2 mm on the upper surface of the single-layer material, placing single-layer material containing 20 %mass boron carbide on upper surface of magnesium alloy powder layer (A), spreading thick magnesium alloy powder layer (B) with thickness of 1-2 mm on upper surface of the single-layer material layered with magnesium alloy powder, placing single-layer material containing 15 %mass boron carbide on upper surface of magnesium alloy powder layer (B), spreading magnesium alloy powder layer (C) with thickness of 1-2 mm, then placing single-layer material containing 10 %mass boron carbide on the upper surface of magnesium alloy powder layer (C), spreading magnesium alloy powder layer (D) with thickness of 1-2 mm on single-layer material, placing single-layer material containing 5 %mass boron carbide on the upper surface of magnesium alloy powder layer (D), performing above sintering process to obtain magnesium-based gradient laminated material, cleaning the outer surface of the magnesium-based laminated composite material, sanding outer surface of the magnesium-based laminated composite material with 400 mesh sandpaper, cleaning outer surface of material with absolute ethanol, drying, testing the tensile strength and elongation of material using electronic universal testing machine and testing hardness of materials by Vickers hardness tester. The graphene oxide composite magnesium-based laminated gradient material has excellent microstructure density, no shrinkage cavities, shrinkage porosity defect, uniform dispersion of graphene oxide and boron carbide, excellent interface bonding, tensile strength of up to 275 MPa, elongation of up to 5.8% and hardness of up to 90 HV. The ball milling process involves adding mixed powder (A) and boron carbide powder to vacuum ball mill tank, adding 40 g grinding balls, so that the mass ratio of the ball to the powder to be mixed is 4:1, closing vacuum ball mill tank, evacuating to pressure of 2 Pa, passing argon gas into tank to keep the pressure in tank at 1 atmosphere, setting ball milling speed to 240 rpm in order to avoid excessive temperature, ball milling twice for 1 hour each time, and stopping ball milling process in interval of 15 minutes to cool down.