Tribological Properties And Bacterial Adhesion Of Stainless Steel And Cu-containing Titanium Nitride Coatings

Food safety has attracted much attention,food microbial infection problem can not be ignored.316 L stainless steel is widely used in food machinery materials,in order to better ensure food hygiene,antibacterial materials can be used in food machinery.Adding Ag,Cu and other metal elements can significantly improve the antibacterial properties of stainless steel.The tribological properties and the adhesion properties of bacteria are the key factors that affect the long-term antimicrobial resistance of food machinery processing materials.Therefore,it is necessary to study the tribological properties and bacterial adhesion properties of 316 L stainless steel and its copper-containing antimicrobial coating.However,there are two problems in the existing research.First,the research mainly focuses on the friction and wear of non-food materials such as metal and stainless steel,which is quite different from the actual situation of food materials.Second,the existing study of Cu-containing coating focused on the specific coating structure.Few studies have studied the grinding of food and coatings,and there is no comparison of the bacterial adhesion property of Cu-containing coating under different conditions.From the reality of food machinery,this paper uses soybean as a representative of food materials to study its friction and wear with 316 L stainless steel and Cu-containing titanium nitride coating.The paper uses soy samples and special fixture to carry out experiments in the vertical universal friction and wear testing machine,The effects of load conditions,speed,travel on the tribological properties of 316 L stainless steel and Cu-containing titanium nitride coatings were investigated.The hardness,surface morphology,coating structure,surface roughness,grinding of the samples and so on were analyzed by means of texture analyzer,microhardness tester,optical microscope,contact angle tester,three-dimensional topography and scanning electron microscope,etc.And the effects of these surface properties on the tribological properties of the materials were investigated.In this paper,the relationship between surface properties and bacterial adhesion properties of 316 L stainless steel and Cu-containing titanium nitride coatings was explored.The research of this paper will help to promote the development of tribological theory in food machinery and provide technical guidance for the selection and application of food machinery materials.The results show that the effect of load and stroke on tribological properties of soybean / stainless steel friction pair is significant.With the increase of the load,thefriction coefficient increases and then decreases,and the friction coefficient is about 0.22.As the load becomes larger,the surface wear of the soybean becomes larger,the wear width of the stainless steel becomes larger,the wear of the abrasive groove is deepened,the surface roughness value of the abrasive is increased,and the wear width is 4.65 mm at 200 N.The test results show that the friction coefficient of the run test is about 0.22 to 0.25.When the test time increases from 0.5 h to 1 h,the wear width of the soybean and stainless steel increases.When the time is increased to 2 h,the wear width and Wear surface changes little,but the surface of stainless steel wear marks increased oxygen content,which indicates that the wear and tear has increased.For tribal properties of soybeans /copper-containing titanium nitride coatings,the tribological properties of the composites were significantly improved compared with those of the soybean / stainless steel friction pair,and the friction coefficient was about 0.08 to 0.13.In the three coatings,the friction coefficient of TiN / TiN-Cu / Cu coating is the largest,the friction coefficient of TiN / Cu coating is the smallest,and the wear width of TiN / Cu coating is obviously reduced.The wear resistance of TiN / TiN-Cu / Cu coating is the best,the wear width is about 1.61 mm,and the surface roughness is about 27.5 nm.The wear mechanism of soybean / stainless steel and soybean / copper-containing coating is mainly abrasive wear,and the wear performance is improved obviously due to the increase of hardness of copper coating and the presence of Cu.The results of bacterial adhesion experiments showed that the bacterial adhesion on the surface of the sample increased with the increase of time,and the surface adhesion of the material was affected by the surface roughness of the material.