62, 310 316 2013 Corrosion Simulation Technology Based on Electrolyte Thermodynamics Kohtaroh Tanaka Simulation Technology Ltd. Corrosion behavior of materials in aqueous solution can be quantitatively analyzed by simulation with electrolyte thermodynamic model, electrochemical kinetic model on material surface and mass-transfer and adsorption models between solution and material surface. This report introduces thermodynamic analysis method by real solution stability diagram, general corrosion rate estimation method by simulated polarization curves and localized corrosion susceptibility evaluation method by repassivation potential with concrete validation examples. Key words : simulation, electrolyte, thermodynamic model, electrochemical, kinetic model, mass-transfer, adsorption, stability diagram, corrosion rate, repassivation potential 1. はじめに CSP Corrosion Simulation Program CSP 1995 Amoco Chevron DuPont Exxon GRI ICI Mobil Shell 9 OLI Systems Inc. Pourbaix ph 1 Nernst 2 a G Gibbs X X i A i Y e e 1 E G 0 Y X G 0 X i GA 0 i RT ln a Y X ln a X i ln a Ai /F e 2 Pourbaix ph H OH 1 H 2 S a 2. 腐食現象の熱力学平衡論的解析 2.1 実在溶液安定領域線図 1),2) 236 0004 1 1 1 1 1 1 Fukuura, Kanazawa-ku, Yokohama, 236 0004 Japan 1 H2S Fe
Vol. 62, No. 9 311 2Metal Activity 1E-6 2.2 安定領域線図と腐食速度の関係 4 300 H 2 O a a Fe Driving Force Partridge 3 3Metal Activity 1E-2 H 2 O b O 2 a b Fe Fe H 2 S Fe Fe 3 O 4 ph FeS FeS 2 metal activity metal activity Pourbaix 1 10 6 metal activity 2 metal activity 1 10 6 3 1 10 2 S S 8 2.3 合金の安定領域線図 2 Fe Ni Cr NiFe 2 O 4 FeCr 2 O 4 NiCr 2 O 4 3. 全面腐食速度の予測モデル 4) 3.1 分極線図のシミュレーション合成と混成電位 i A i C 4 300
312 i corr Butler - Volmer Kinetics 5 CO 2 18 Fe 3 Fe BDD Bockris-Drazic- Despic OH i Fe i 0 Fe exp α Fe F E E 0 Fe /RT 3 i 0 Fe i Fe a OH a Oc H2 / 1 K OH a OH α Fe i 0 Fe i Fe E 0 Fe Fe ck OH E 0 Fe K OH α Fe i Fe 3 ph 6 Na 2 SiO 3 7 9 10 HNO 3 C-22 Rate [g/(m 2 d)] 5 4 3 2 1 0 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 N Na 2SiO 3 6 7 Fe - 5 Fe 8
Vol. 62, No. 9 313 100 Rate (mm/y) 10 1 0.1 Sridhar et al. (1987) 20 wt% HNO3, 353 K Calculated 0.01 0 1 2 3 4 5 wt.% HF 10 8020 wt HF C 22 9 HF HNO 3 HF HF 2 HF 11 12 NO 3 HF NO 3 HF 5,6 3.2 シミュレーション推算値と実測値の比較 2 N 2 N 2 O 2 ppb H O 2 11 HF 12 1.6 HF
314 Scan Rate Scan Rate 3.3 流れと物質移動の取り扱い 7) 2 3 PorosityTortuosity 19) 3.4 スケール生成の影響 FeCO 3 FeS CaCO 3 CaSO 4 FeCO 3 FeS 811 3.5 混合溶媒, 非水溶媒溶液環境への拡張 65 mol 4. 局部腐食予測モデル 12) 4.1 再不動態化電位 13 M MX MO 1 5 4 i rp l n ξ FErp k n α FErp 1+ 1 θ exp = θ exp i p irp RT irp RT 4 E rp i rp i p kα n l kl 14 316 15 Fe Ni Cr Mo W N 15 95 13 13
Vol. 62, No. 9 315 Erp (SHE) 1.0 0.8 0.6 0.4 0.2 0.0 0.42 M Cl 3 M Cl 4 M Cl -0.2 0.0001 0.001 0.01 0.1 1 10 a NO3 Erp (SHE) 1.0 0.8 0.6 0.4 0.2 0.0 80 C 95 C 105 C -0.2 0.10 1.00 10.00 acl 125 C 150 C 175 C 14 Cl NO 3 17 Al Erp(SHE) x(cr) 1.0 0.8 0.6 0.4 0.2 0.0-0.2-0.4 0.0001 0.001 0.01 0.1 1 10 a Cl 15 95 0.20 0.18 0.16 0.14 0.12 0.10 0.08 0.06 Alloy 600 0.04 Carbide = Cr 7 C 3 0.02 Data: Was and Kruger (1985) 0.00 0 200 400 600 800 1000 Distance from grain boundary, nm 16 Cr 4.2 材料熱履歴の影響 Cr Mo Alloy 600 Cr 16 22, exp 22, generalized 276, exp 276, generalized 625, exp 625, generalized 825, exp 825, generalized 690, generalized 600, exp 600, generalized 800, generalized 254SMO, exp 254SMO, generalized AL6XN, exp AL6XN, generalized 2205, generalized 316L, exp 316L, generalized 304L, generalized s-13cr, exp s-13cr, generalized T=973 K, t=1h T=973 K, t=1h, cal T=973 K, t=10h T=973 K, t=10h, cal T=973 K, t=30h T=973 K, t=30h, cal T=973 K, t=100h T=973 K, t=100h, cal T=873 K, t=250h T=873 K, t=250h, cal T=1073 K, t=0.42h T=1073 K, t=0.42h, cal 14 4.3 局部腐食の進展速度 3 17 Al X Y Z 3 15 3 16 18 FeCl 3 C-276 m Worst Case Scenario
316 100 Int. Nickel Co. (1972) 298 K Rate (mm/y) 10 1 0.1 Int. Nickel Co. (1972) 303 K Int. Nickel Co. (1972) 338 K Inco Alloys Int. (1986) 323 K Inco Alloys Int. (1986) 348 K 298 K, cal. max. pit rate 303 K, cal. max. pit rate Parameters Corrosion Potential Pitting Critical Potential SCC 0.01 323 K, cal. max. pit rate 338 K, cal. max. pit rate Strain Rate 0.001 0 1 2 3 4 5 6 m (FeCl 3 ) 348 K, cal. max. pit rate Time (Environmental Variables) 19 18 FeCl 3 C- 276 Con servative 4.4 応力腐食割れ発生予測への応用 19 Det Norske Veritas U.S.A.Inc. 17 5. おわりに 3.2 参考文献 1 A. Anderko et al., Corrosion, 53, 43 1997. 2 A. Anderko et al., Shreir s Corrosion 4th edition, 2, 1591, Amsterdam Elsevier 2010. 3 Partridge, E. et al., Trans. Am. Soc. Mech. Eng., 61, 597 1939. 4 A. Anderko et al., Corrosion, 57, 202 2001. 5 M. A. Blesa et al., Chemical Dissolution of Metal Oxides, CRC Press, Boca Raton, FL, 1994. 6 N. Sridhar et al., Materials Performance, 26 10 17 1987. 7 J. Newman et al., Electrochemical Systems, 3rd edition, Prentice Hall, Englewood Cliffs, NJ, 2004. 8 S. Nešić et al., Corrosion, 59, 616 2003. 9 S. Nešić et al., Corrosion/2005, paper 05556, NACE International, Houston, TX, 2005. 10 W. Sun et al., Corrosion/2007, paper 07655, NACE International, Houston, TX, 2007. 11 A. Anderko et al., Corrosion/99, paper 31, NACE International, Houston, TX, 1999. 12 A. Anderko et al., Corrosion Science, 46, 1583 2004. 13 A. Anderko et al., Corrosion Science, 50, 3629 2008. 14 A. Anderko, et al., US Department of Energy, proect DE- FC36-04GO14043 final report, September, 2007. 15 G. Engelhardt et al., Corrosion Science, 46, 1159 2004. 16 A. Anderko, et al., Corrosion Science, 46, 1583 2004. 17 DET NORSKE VERITAS, Proposal for Joint Industry Proect, 2010. 18 A. Anderko et al., Shreir s Corrosion 4th edition, 2, 1609, Amsterdam Elsevier 2010. 19 A. Anderko et al., Shreir s Corrosion 4th edition, 2, 1618, Amsterdam Elsevier 2010. 2013 3 31 要 旨 キーワード