Investigation On Technology And Properties Of Laser Cladding WC/Diamond/Co-Cr-Based Composite Gradient Coating On High Speed Steel Surface

Abrasion and impact-induced tooth crack are the main failure mechanisms of shield cutter.Laser cladding technology is used to prepare the high hardness composite gradient coating on the surface of high toughness high speed steel."Hard and tough complementary"was realized.It can be used as an alternative scheme to the shield machine cutter.WC/diamond/Co-Cr-based composite coatings are prepared on the surface of high-speed steel.The effects of different process parameters on the geometric parameters,dilution rate and wetting angle of single channel cladding layer are studied.L₉(3⁴)orthogonal test is designed.The influence degree of each factor on the comprehensive performance of the cladding layer is studied by orthogonal test range analysis,and the optimal process parameters are obtained.At the same time,the optimal lap rate is determined by multi-pass lap test.WC/diamond/Co-Cr-based composite gradient coatings are prepared by using optimized process parameters.The comprehensive properties of composite gradient cladding are analyzed from the aspects of organization,composition,hardness,wear resistance and corrosion resistance.The test results show that the cladding layer is mainly composed of?-Co?C?M₂₃C₆(M means of Cr?Co?Mo)?W₂C?M₆C(Co₃W₃C,Fe₃W₃C)and a small amount of the WC phase.The grain size of the gradient composite cladding layer is gradually refined from the bottom to the top.The chemical and metallurgical combination is realized.The gradient change of interfacial element between WC,diamond and bond phase improves the mechanical properties of cladding layer.The main wear pattern of the surface of the gradient cladding layer is abrasive wear with slight adhesion wear and peeling wear.The uniform distribution of high hard heterogeneous particles such as diamond and WC is the main reason for the improvement of wear resistance of cladding layer.The grain size of composite cladding layer varies gradient from bottom to top.Mechanical vibrations contribute to heterogeneous nucleation.Grain refinement is realized in the cladding layer assisted by mechanical vibration,and the cellular/equiaxial crystal zone at the interface is widened.There are dendrite fracture and interlacing.The horizontal mechanical vibration equiaxial crystal belt is narrow and the dendritic crystal growing continuously at the interface improves the interface connectivity of the cladding layer.There are good wear resistance and corrosion resistance of the cladding layer aided by horizontal mechanical vibration.