Microstructure Properties And Corrosion Resistance Of Coatings Prepared By High Speed Laser Cladding On Mg Alloy

Magnesium alloys are widely used because of their high specific stiffness,low density,good die casting performance,and ease of processing.However,the low hardness,poor wear resistance,and corrosion resistance of magnesium alloys restrict the development of magnesium alloys.An important research direction of laser cladding material surface modification technology.Laser high-speed cladding has higher deposition efficiency than traditional laser cladding,and the coating can obtain better corrosion resistance.Using laser high-speed cladding technology can effectively solve magnesium alloys The current situation of poor wear and corrosion resistance is of great significance to promote the application of magnesium alloys in important fields.In this paper,a laser cladding system composed of Tru Diode 4000 W semiconductor fiber laser,ABB six-degree-of-freedom robot(IRB4600-M2004)and Sulzer Metco Twin10 C double barrel powder feeder is used to prepare AlSi12 coating on the surface of AZ91 D magnesium alloy by high-speed laser cladding technology And AlSi12 + TiN composite coating.Observe the microstructure of AlSi12 coating and AlSi12 + TiN composite coating by optical microscope and scanning electron microscope,determine the phase composition of Al-Si coating by X-ray diffractometer,use micro hardness tester,electrochemical workstation and The high-temperature and high-speed friction and wear testing machine detects and analyzes the hardness,corrosion resistance and wear resistance of the Al-Si coating.The research results show that when the laser power is 225W?275W,the laser scanning rate is 1.8m / min,the powder feeding rate is 2r / min,the defocusing amount is + 4mm,and the overlap rate is 40%,the high-speed laser cladding on the surface of the AZ91 D magnesium alloy Al-Si coatings(AlSi12 coatings,AlSi12 +23% TiN and AlSi12 + 17% TiN coatings)have high metallurgical quality,and Mg-Al metals such as Mg2 Si,Mg2Al3,?-Mg and Mg17Al12 mainly exist in Al-Si coatings Between compounds.The average microhardness of AlSi12 coating is 160HV0.2,the average microhardness of AlSi12 + 17% TiN coating is 190HV0.2,and the average microhardness of AlSi12 + 23% TiN coating is 210HV0.2.The presence of hard phases such as Mg2 Si,?-Mg,and Mg17Al12 in the coating and coating increases the hardness of the coating,and the coating increases the surface hardness of the AZ91D magnesium alloy by about 3 to 4 times.The significant improvement of the surface hardness of the Al-Si coating improves the wear resistance and load-bearing performance of the rare earth magnesium matrix,of which the AlSi12+23%TiN coating has the most obvious improvement.The Al-Si coating significantly improves the corrosion resistance of the AZ91 D magnesium alloy.The self-corrosion potential of the AlSi12 coating is 0.219 V higher than that of the AZ91 D magnesium alloy.The AlSi12 + 17% TiN coating has a self-corrosion potential of 0.288 V higher than that of the AZ91 D magnesium alloy.AlSi12 The + 23% TiN coating self-corrosion potential Ecorr is 0.683 V higher than that of AZ91 D magnesium alloy.AlSi12 + 23% TiN coating has the most obvious improvement in the corrosion resistance of rare earth magnesium.The self-corrosion current density is 2 orders of magnitude lower than that of AZ91 D magnesium alloy.the above.