YG6. Murakami 30 min. Effect of Cobalt-Etched Treatment on the Adhesion between Diamond Films and WC Co Cemented Carbide

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1 16 / ( ) YG3 YG6 Murakami 30 min 3H 2 SO 4 7 H 2 O 2 30 s YG6 TG135.5 O484.1 A (2003) Effect of Cobalt-Etched Treatment on the Adhesion between Diamond Films and WC Co Cemented Carbide YANG Li 1, YU Zhi-ming 1, YIN Lei 1, LI Yong-xia 2, ZOU Dan 2 (1. School of Materials Science and Engineering, Central South University, Changsha , P.R.China; 2. Hunan Ying Zhou Nonferrous Metals Hi-Tech. Limited Company, Changsha , China) Abstract Diamond films were deposited on Tungsten Carbide-3%Cobalt and Tungsten Carbide-6%Cobalt with different two-step surface pretreatments by Hot Filament Chemical Vapor Deposition (CVD). The surface morphology, composition and adhesion of the diamond films were investigated by means of Scanning Electron Microscope (SEM), Energy Dispersion Spectroscope(EDS) and Rockwell hardness tester. The results showed that using Murakami reagent for etching 30 min, then H 2 SO 4 : H 2 O 2 =3:7 solution for removing cobalt 30s, the diamond nucleation density of these two kinds of samples is greatly increased, resulting in a good adhesion between diamond film and the substrate. Under the same pretreatment conditions, the quality of the diamond coating on the serious of WC 6 %Co samples is much better. The adhesive strength of diamond film and the cemented carbide can be greatly enhanced by reducing the content of cobalt on the surface of WC substrate. Key words diamond films; cemented carbides; two-step pretreatment; adhesion 0 CVD [3-5] [1 2] 8 000~ HV Co Murakami CVD Co (1978 ) ( ) Co [6] [7 R.Bichle 8] Co 3 % 10 %

2 Co Co 6 % % 1 YG3 YG6 CSU550 Co CVD ìm mm 24 mm 30 mm 1.1 D08 3B/ZM YG3(WC Co3 %) YG6(WC Co6 %) 7.5 mm 7.5 mm 3.0 mm 1# YG3 2# YG6 3# YG3 4# YG6 5# YG3 6# YG6 Table 1 Various pretreatments of the WC substrates and the parameters of thin film deposition Murakami K 3 [Fe(CN)] 6 KOHÓH 2 O=1Ó1Ó10 10 min 3H 2 SO 4 +7 H 2 O 2 30 s 0.5 Treat1 ìm 15min Murakami K 3 [Fe(CN)] 6 KOHÓH 2 O=1Ó1Ó10 20 min 3H 2 SO 4 +7 H 2 O 2 30 s 0.5 Treat2 ìm 15 min Murakami K 3 [Fe(CN)] 6 KOHÓH 2 O=1Ó1Ó10 30 min 3H 2 SO 4 +7 H 2 O 2 30 s 0.5 Treat3 ìm 15 min 8mm H % 30sccm CH % 1sccm Pa 7 h MFC MFC MFC 1.3 KYKY 2800 Finder N 20 s 2 1 CVD Fig.1 Schematic diagram of the HFCVD reactor Murakami 10 min YG3 YG6 6 ìm

3 18 2(a) 30 min 5# 6# (b) 3# 4# 2(e) (f) 5# 2(c) (110) (111) 6# (d) Murakami (111) (a) 1# (c) 3# (e) 5# (b) 2# (d) 4# (f) 6# Fig.2 Surface morphology of diamond coatings after various pretreatments WC 1 WC Co 2 Co 2 Treat3 2~3 ìm Murakami WC 30 min 3H 2 SO 4 +7H 2 O 2 Co 30 s Co CVD 600 N 20 s YG3 Murakami min Co 2.58 % [9] 3(a) 2 YG6 Co 3.92 %

4 # 3(b) 3# 4# Treat3 3(c) (d) 3# 30 min 5# 6 (a) 1# (c) 3# (e) 5# (b) 2# (d) 4# (f) 6# Fig.3 SEM images of the indentation crack morphology for diamond coating on different pre-treated substrates 200 Fig.4 4 [10] 4 YG3 YG6 Co The relationship of Co content and various pretreatments of substrates - CVD Co WC YG6 YG3 6# 6 % 0.82 % 5# 3 % % YG6 - YG3 3(e) (f) YG6 YG Co

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