An enhanced ceramic conversion treatment of Ti6Al4V alloy surface by a pre-deposited thin gold layer

Impact of the amount of the gold layer on the tribological performance of the ceramic conversion treated CP-Titanium

“…Thanks to the high a nity of Ti for O, the oxidation of titanium alloys is dominated by the inward diffusion of O 2− and the outward diffusion of Ti 4+ [19]. In our previous study, we found that with the existence of a gold layer on the surface of the titanium alloy, the outward diffusion of Ti ions is promoted to provide more fresh titanium atoms to react with oxygen [12]. Gold has an atomic number of 79 with the electron con guration of [Xe] 4f14 5d10 6s1, and it has a multi-oxidation state.…”

“…However, the lengthy thermal-chemical process of CCT ( 50 to 100 hours at temperatures ranging from 580 to 700°C) can result in grain growth of the matrix which negatively affects its mechanical properties [3,10,11]. In previous research, we found that gold can promote the outward diffusion of titanium at elevated temperatures and therefore accelerate the oxidation process of CPTi and Ti6Al4V alloys [12][13][14]. Gold is also one of the most promising solid lubricants due to its long-term stability and frictional properties [15].…”

Impact of the Amount of the Gold Layer on the Tribological Performance of the Ceramic Conversion Treated CP-Titanium

“…Thanks to the high affinity of Ti for O, the oxidation of titanium alloys is controlled by the dissolution of oxygen in the metal and the outward diffusion of titanium [21,22]. In our previous study, we found that with the existence of a gold layer on the surface of the titanium alloy, the outward diffusion of Ti ions was promoted to provide more fresh titanium atoms to react with oxygen [13]. Gold has an atomic number of 79 with the electron configuration of [Xe] 4f14 5d10 6s1, and it has a multi-oxidation state.…”

“…After treatment, it was cooled down to room temperature in the furnace. Based on our previous research [13,20], three treatment durations (3, 40 and 80 h) at 620 °C were executed to compare the impact of the different amounts of gold on the CCT (Table 1). A higher temperature CCT (660 °C/3 h) was also used to further verify the impact of gold on the CCT of CP-Ti.…”

“…However, the lengthy thermalchemical process of CCT (50 to 100 h at temperatures ranging from 580 to 700 °C) can result in grain growth of the matrix which negatively affects its mechanical properties [3,10,12]. In previous research, we found that gold promoted the outward diffusion of titanium at elevated temperatures and therefore accelerated the oxidation process of CP-Ti and Ti6Al4V alloys [13][14][15]. Gold is also one of the most promising solid lubricants due to its long-term stability and frictional properties [16].…”