Tribological Properties Of Ni60 Alloy Coatings Preparated By High-velocity Oxygen-fuel Spraying

Stainless steel materials have a wide range of applications in the mechanical industry.However,the low surface hardness and poor wear resistance limit the performance of stainless steel.The use of high-velocity oxygen-fuel spraying technology to prepare wear-resistant coatings on the surface can expand the application field of stainless steel.As a coating material,Ni60 alloy has the corrosion resistance and high temperature resistance of not less than stainless steel,and it has good wear resistance.The replacement of the spray gun of high-velocity oxygen-fuel spraying equipment,the process parameters often seriously affect the performance of the coating.Therefore,improving the supersonic flame spraying process to prepare Ni60 alloy coating on the surface of stainless steel to reduce friction and improve wear resistance has important academic significance and practical reference value.Combining simulation and experiment,this article proposes to control the flow of kerosene and oxygen of JP8000 high-velocity oxygen-fuel spraying system to prepare Ni60 alloy coating on the surface of 316 stainless steel,and then to study the influence of process parameters on the tribological properties,mainly carried out the following work:Based on 8220 the model of the structure of the spray gun was established.The CFD software Fluent was used to numerically analyze the gas flow field of the flame flow.The distribution of gas flow field in the combustion of the spray gun and the influence of kerosene and oxygen flow parameters on the flame flow were studied.The results show that when the oxygen flow rate is 38m3/h,the temperature value and flame flow velocity value generated by combustion are relatively large.Among them,when the kerosene flow rate is 4.2g/s,the flame stream temperature can reach 3105K and the flame stream velocity can reach 2286m/s,When the oxygen flow rate is fixed,the temperature and speed of the flame flow will peak with the change of the kerosene flow rate.When the kerosene flow rate exceeds this value,the temperature and speed of the flame flow will decrease.Since the oxygen flow is difficult to control accurately during preparation,the melting point of Ni60 alloy is high,so in this article,the processing parameters of oxygen flow rate fixed at 38m3/h and kerosene flow rate at3.6g/s,3.8g/s,4.0g/s,4.2g/s and 4.4g/s are selected as the object of follow-up experimental research.JP8000 high-velocity oxygen-vuel spraying equipment was used to prepare a uniform Ni60 alloy coating on the surface of 316 stainless steel.The TMHV-1000 microhardness tester was used to investigate the microhardness variation of coatings with different processing parameters.The composition of the coating was analyzed using a scanning electron microscope combined with a JSM-6490LV energy spectrometer,the result shows there are different degrees of unmelted powder particles in the coating,and there are few unmelted particles in the coating under the preparation conditions of high flame flow temperature;the coating hardness is high under the preparation conditions of high flame flow speed;there are hard phases such as?-Ni,Fe Ni₃,Fe Ni in the coating.Under different lubricating conditions,using the CFT-I high-speed reciprocating friction and wear testing machine to study the general rules of Ni60 alloy coating against 316 stainless steel to reduce friction and wear resistance;Combined with the VHX-2000C ultra-depth 3D microscopic system,the wear variation of Ni60 alloy coatings prepared with different processing parameters was investigated,and the effect of sliding speed on tribological properties was analyzed.The results show that under dry friction conditions,the Ni60 alloy coating has a small friction coefficient relative to the surface of 316 stainless steel,and its wear resistance is remarkable;Under oil lubrication conditions,the friction coefficient of Ni60alloy coating is close to that of 316 stainless steel.Optimizing the preparation parameters of Ni60 alloy coating can achieve a certain friction reduction effect,and the wear resistance performance is good;The higher sliding speed is beneficial for the friction pair to reduce the friction coefficient.Within the range of the kerosene flow parameters studied,the kerosene flow is 4.2g/s Ni60 alloy coating has the best anti-friction and anti-wear effects.