Preparation And Properties Of Plasma Sprayed 601NS-NiCrBSi Composite Coating At The Maximum Heat Flow Rate Of Cu Alloy Mold Plate

The mold is the core device of the continuous casting machine,and the stability and reliability of its operation have an important influence on its service life,slab casting quality,casting speed and work rate,and production cost.Friction and wear of the copper surface and thermal cracks at the meniscus are the main forms of mold failure.The surface treatment of the mold copper plate to meet the homogeneity of the heat transfer of the mold copper plate,and improve its wear resistance,is of great significance for prolonging the service life of the crystallizer and improving the quality of the billet.In order to develop a mold copper composite material with low thermal conductivity and excellent wear resistance,it was applied to the meniscus of the mold.CoNi CrAlY/601NS-NiCrBSi composite coating was prepared on the surface of continuous casting mold copper alloy?Cr-Zr-Cu?by using the self-made601NS-Ni CrBSi mixed powder and atmospheric plasma spraying technology.The results are summarized as follows:?1?The three coatings prepared by plasma spraying showed good bonding performance and excellent thermal shock resistance.The bonding strength of A-2coating was 19.379 MPa,and the bonding mode is mainly mechanical bonding.The AlSi phase and the NiCrBSi phase in the coating structure are uniformly distributed and form a strong network structure,so the coating has good bonding performance.The A-2bullet coating was water quenched at 500°C,650°C,and 800°C.The coating failure experienced 122,65,and 30 thermal shock cycles,respectively;the round cake coating experienced 133,respectively.Thermal shock cycles of 70 and 35 cycles have higher thermal shock stability than the other two coatings.?2?The 601NS-NiCrBSi composite coating has good thermal insulation properties.The average thermal conductivity coefficient of three different Al-Si-polyphenylene composite coatings were 1.723W/?m·k?,1.287W/?m·k??1.19W/?m·k?,respectively.The porosity of the layers was 3.89%,7.56%and 9.25%,respectively.That is,as the content of Al-Si polyphenyl ester increases,the porosity of the coating increases accordingly,the thermal conductivity of the coating becomes smaller,and the thermal insulation of the coating increases.?3?The composite coating after Al-Si polyphenyl ester shows excellent wear resistance.When the friction pair is GCr15,the friction coefficients are 0.38,0.35,and0.3,respectively.Compared with the friction coefficient of the substrate,0.55,the friction coefficient of the three kinds of samples is relatively low.The 30%601NS-NiCrBSi coating had the lowest abrasion loss,only 0.0015 g,and the minimum wear scar width was only 0.3 mm.When the friction pair was Al₂O₃,the friction factors were 0.42,0.30,and 0.25,respectively.The friction coefficient of the matrix is 0.56,and the friction coefficient of the three specimens is relatively low.The wear loss of the30%601NS-NiCrBSi coating was the smallest,only 0.0321 g,and the width of the wear scar was also the smallest,only 0.6 mm.The wear mechanism was the abrasive wear caused by the brittle fracture.?4?The overall performance of the coating prepared from the NiCrBSi mixed powder containing 30%Al Si polyphenyl ester is the best.