▎ 摘　　要

NOVELTY - Preparation of graphene reinforced titanium alloy bar involves weighing 7-10% zirconium, 16-18% niobium, 1.5-2.5% iron, 0.5-0.8% chromium, 0.5-0.9% gallium, 0.25-0.75% tin, 0.02-0.07% hafnium, 1-2% tantalum, 1-2% aluminum, 0.25-0.45% vanadium, 0.1-0.18% boron, 0.12-0.18% cerium, and balance titanium; melting components in vacuum arc furnace; stirring; casting into ingot; putting ingot into vacuum furnace; heat treating under argon gas protection at 200-250 degrees C/hour at 920-940 degrees C for 6-10 hours; gradually cooling; and forging coated molding surface of ingot. USE - Preparation of graphene reinforced titanium alloy bar used as alternative material for bone, joints and artificial tooth root and other hard tissue repair. ADVANTAGE - The method has optimized heat treatment and spraying coating processes, and has refined preparation steps, thus ensuring quality and excellent mechanical properties of alloy. DETAILED DESCRIPTION - Preparation of graphene reinforced titanium alloy bar comprises: (A) preparing ingot by weighing 7-10% zirconium, 16-18% niobium, 1.5-2.5% iron, 0.5-0.8% chromium, 0.5-0.9% gallium, 0.25-0.75% tin, 0.02-0.07% hafnium, 1-2% tantalum, 1-2% aluminum, 0.25-0.45% vanadium, 0.1-0.18% boron, 0.12-0.18% cerium, and balance titanium; melting components in vacuum arc furnace; stirring; casting into ingot; putting ingot into vacuum furnace; heat treating under argon gas protection at 200-250 degrees C/hour at 920-940 degrees C for 6-10 hours; gradually cooling at 120-150 degrees C/hour at 550-580 degrees C for 2-6 hours, at 80-90 degrees C/hour at 280-320 degrees C for 2-5 hours, further cooling at 50-65 degrees C/hour at 180-190 degrees C for 2-5 hours; and cooling at room temperature with furnace to obtain ingot; (B) forging coated molding surface by coating billet surface with boron nitride as main component to prevent oxidation during high temperature processing and to increase lubrication; free-forging ingot at 1000 tons in hydraulic machine at 900-1000 degrees C for 1-2 hours; final forging at 660-720 degrees C; repeatedly forging in side length to obtain 200-300 mm square billets; cooling at room temperature; grinding billet surface defects after heating at 900-950 degrees C to obtain upsetting and stretching deformation of 3-6 times; final forging at 770-810 degrees C until pass deformation of 20-45% is obtained and 70-130% total cumulative deformation is attained; cooling forged billet at room temperature; grinding surface defects; heating at 700-740 degrees C; forging upsetting and stretching for 3-6 times until pass deformation of 15-30% is achieved and cumulative total deformation of 55-110% is attained; cooling upset forged billet at room temperature; grinding surface defects; heating at 680-720 degrees C; forging upsetting and stretching for 2-3 times until pass deformation of 40-50% is achieved; performing final pull duration forging chamfering; rounding; cooling at room temperature; grinding surface defects; reheating at 730-740 degrees C; chamfering and rounding; and stretching and forging to obtain bar with diameter of 40-80 mm; (C) heat treating by putting bar in bar box-type resistance furnace with treatment solution; heat treating at 860-900 degrees C for 15-45 minutes; water quenching in vacuum furnace under protection of argon gas; heating at 450-480 degrees C for 2-3 hours; performing gradual furnace cooling at 280-310 degrees C for 3-4 hours, and at 180-220 degrees C for 5-6 hours; cooling with water; and aging; (D) pretreating surface by washing heat-treated alloy bar with 90-100 degrees C hot water; water cooling at room temperature; cleaning; drying with compressed air; blowing quartz sand to remove machining marks and to increase roughness; immersing titanium alloy bar in alkaline solution at 350-550 degrees C for 30-60 minutes, in which alkaline solution is mixed solution of 70-80 wt.% sodium hydroxide and 20-30 wt.% sodium nitrate; pickling bar surface at 40-50 degrees C for 15-45 minutes with acid liquid composition comprising 20-30 pts. wt. of 98% concentrated sulfuric acid, 6-8 pts. wt. of 36.5% hydrochloric acid, 1-2 pts. wt. dialkyl imidazoline, 1-3 pts. wt. ethylenediamine, and 30-60 pts. wt. water; and immersing titanium bar in acid solution at 90-150 degrees C for 15-20 minutes for passivation treatment, in which acid solution comprises 150-200 g/l sodium nitrate and 15-45 g/l sodium fluoride aqueous solution to control iron ion concentration at less than 20 g/l; (E) preparing graphene film by putting titanium bar in isopropanol ultrasound; rinsing with ultrapure water; slowly soaking bar into piranha solution at 30-60 degrees C; standing; removing treated titanium bar and further soaking in piranha solution at 30-60 degrees C for surface hydroxylation; rinsing alloy bar with deionized water; soaking in aminosilane solution; putting graphene oxide powder into distilled water; ultrasonic dispersing to obtain colloidal graphene oxide solution with concentration of 0.1-6.0 mg/ml; immersing titanium alloy bar in colloidal graphene oxide solution in closed vessel; continuously maintaining at constant temperature; immersing titanium bar in mixed solution of hydrohalogenic acid and phosphoric acid; heating in sealed container; repeatedly washing with deionized water until pH of water washing is neutral; and drying titanium alloy bar to obtain titanium alloy bar having surface coated with graphene film; and (F) spraying surface coating by preparing coating materials comprising 60-80 pts. wt. titanium oxide powder, 0.1-1.0 pts. wt. silver powder, 15-20 pts. wt. wollastonite powder, 0.1-0.5 pts. wt. silver oxide powder, and 2-4 pts. wt. titanium diboride powder; spraying coating via atmospheric plasma spraying onto surface of titanium alloy bar under protection of argon gas at flowrate of 15-30 l/minute, hydrogen gas at flowrate of 15-20 l/minute, and argon carrier gas flowrate of 0.5-2.5 l/minute, spraying distance of 40-60 mm, feed rate of 5-10 g/minute, spraying current of 450-600 A, and coating thickness of 0.5-3 mm; heat treating coated titanium rod in vacuum furnace under argon gas protection at 550-650 degrees C for 1-2 hours; cooling at 150-200 degrees C for 24-48 hours; and cooling with furnace to obtain graphene reinforced titanium alloy bar.