Evaluation of surface properties of stainless steel brackets coated with Ti and Ag by the PVD method

To evaluate the effectiveness of Ti and Ag coating on stainless steel orthodontic brackets this study was conducted. 75 stainless steel orthodontic bracket were divided into five groups of 15 samples each. The first group was left uncoated as control group. PVD coating method was used in this experiment. Two groups of 15 brackets were Ag-coated with 60nm an 100nm thickness each. The remaining 2 groups were Ti-coated with again 60nm and 100nm thickness each. To evaluate the surface properties 3 samples were selected from each group randomly, and were put to friction test. For surface morphology evaluation, SEM and AFM were used on 1 sample selected from each group. The friction test indicates that, coating increases the friction force. Furthermore by increasing the coating thickness , a greater increase in friction force was observes , regardless of the type of coating. AFM test indicated that , by increasing the thickness of the coating layers, grain size and surface roughness were reduced. Furthermore , SEM test revealed that coating either with Ti or Ag results into less pores in relevance to uncoated samples. The SEM results proved that by increasing the coating thickness , grain size was reduced. .