Step Synthesis Method for Diamond Films on Tungsten Carbide Substrate Surface by Combustion Flame

Abstract

A combustion flame method enables the synthesis of diamond using acetylene-oxygen gas (C 2 H 2 /O 2 ) combustion flame in ambient air. Recently, tungsten carbide (WC) is used as cutting tools in the machining industry. In this study, diamond films were synthesized by combustion flame on WC surfaces. However, it was difficult to synthesize the diamond films on the WC substrate surfaces. Therefore, in order to synthesize the diamond film, a two-step synthesis method was proposed. In this method, the film surface temperature and the distance of the flame inner cone from the surface for each step are changed during the synthesis. The first step was setting the film temperature to 1273 K, the second step was setting to 1223 K. The distance of the flame inner cone from the surface was changed for each step (Case 1 ; the first step : d = 7.0 mm, the second step : d = 7.0 mm, Case 2 ; the first step : d = 7.0 mm, the second step : d = 7.5 mm, Case 3 ; the first step : d = 7.5 mm, the second step : d = 7.0 mm). In the Case 1 and 2, the delamination-free film was synthesized on the WC surfaces, and diamonds were synthesized. However, in the Case 3, the film delamination occurred, and good diamond films were not synthesized.

Influence of Diamond Seed Attachment Processing on Diamond Films Synthesized on Tungsten Carbide Substrate by Flame Combustion

“…During the synthesis, the diamond film synthesis and delamination were affected when the distance was altered, because there was a change in the acetylene feather area. We confirmed that delamination at d = 7.0 mm during diamond film synthesis could be effectively prevented [14][15][16]. Therefore, diamond films were synthesized at d = 7.0 mm.…”

“…The synthesis conditions are listed in Table 1. These conditions have been determined and reported previously [14][15][16], and are believed to be the optimum conditions for preventing delamination during the synthesis of diamond films. The ratio of the oxygen flow rate (F o = 63.8 cm 3 /s) to acetylene flow rate (F a = 70.9 cm 3 /s) was set to R f = F o /F a = 0.90, because delamination-free crystallite growth could be realized at R f = 0.90 [14][15][16].…”

“…In this experiment, the film surface temperature was changed twice during synthesis [14][15][16]. The first step of the method was performed at 1273 K to achieve high bonding strength.…”

“…Therefore, diamond films were synthesized at d = 7.0 mm. The processing time for each of the two steps in the method used was set to 1200 s, and the total synthesis time for both steps was set to 2400 s [14][15][16]. The average thickness of the synthesized films was 30 μm/h.…”

“…We have also synthesized diamond films on a Ti substrate for dental implants using the flame combustion method [13]. In a previous report, diamond films were synthesized on WC substrates via flame combustion [14][15][16]. However, the synthesis of diamond films on WC substrates is difficult.…”