Study On Interface Mechanical Properties And Thermal Stress Of WC Coatings

The rapid development of modern mechanical industry,prompting tool widely used in various industries,but as the industry towards high precision,high efficiency,high quality,development direction,such as processing object on the performance of the cutting tool demand is higher and higher,the single tool material already can't satisfy the need of high performance material,so in order to improve the cutting tool performance,vacuum coating technology application.Cemented carbide coating refers to a layer or multiple layers of metal or nonmetallic compound film(such as Ti C,Ti N,etc.)covered on the surface of cemented carbide.In this way,the contradiction between the strength and hardness of the tool can be well solved.In the process of preparation of cemented carbide coatings,there is a lack of theoretical basis for the study and explanation of the interface formation mechanism.Therefore,in order to improve the product quality of the coating itself,it is very necessary to find a suitable method to analyze the formation mechanism of the coating interface.This paper summarizes the current research methods on the basis of the principle of primacy of the coating and substrate interface combination properties and thermal stress coating were studied with finite element method(fem)related situation,according to the different coating composition and thickness gradient composite coating more model is established,and based on the bonding performance and residual thermal stress are two aspects,the three aspects,such as theory analysis,simulation analysis and test research.Firstly,according to the different types of substrates selected in the preparation process of ta-C and hydrogen-containing DLC coatings,the first-principles method based on density functional theory was used to study the interface properties of WC/?-Ti and WC/Cr.The research contents include interface binding energy,interface stability,interface electronic structure and interface binding mechanism.It is found that WC(001)/?-Ti(001)interface and WC(100)/Cr(001)interface are the best combination interfaces.Considering the different stacking modes of WC(001)/?-Ti(001),WC(100)/Cr(001)and the different types of atoms(C-terminations and W-terminations)that WC is used to form the interface terminal,a total of six WC/?-Ti interface models and 16WC/Cr interface models are established.The results show that the binding energies at the WC/?-Ti interface(2.38-9.53J/m^2)are generally lower than those at the WC/Cr interface(4.24-12.14J/m^2).Secondly,based on the finite element method,the thermal stress mitigation mechanism of cemented carbide gradient coating was analyzed by Ansys Workbench software,and the effects of two cemented carbide coatings(WC/Ti/Ti C/ ta-C and WC/Cr/Si C/ hydrogencontaining DLC)on the thermal stress field were compared.The calculation results prove that the design of the two multi-gradient composite coatings is reasonable,and the thermal stress value of WC/Cr/Si C/ hydrogen-containing DLC coating is lower than that of WC/Ti/Ti C/ ta-C coating.Finally,based on the analysis of theoretical results,the accuracy of the simulation is verified by experimental comparison.