反复熔铸对镍铬烤瓷合金电化学腐蚀性能影响的研究

Effect of recasting on the electrochemical corrosion properties of the Ni-Cr alloy for porcelain-fused-to-metal restoration

目的探讨反复熔铸对镍铬烤瓷合金在人工唾液中电化学腐蚀行为的影响。方法试样由镍铬烤瓷合金分别经过1、2、3、4及5次熔铸(即Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ代试样)后,再经铜导线焊接、聚甲基丙烯酸甲酯包埋、测试面氧化铝砂纸磨光和布轮抛光而成。试样浸泡于人工唾液中[温度为(37.0±1.0)℃,pH为7.4±0.1]24h后,参考ISO10271(2001)标准,采用动电位极化曲线法测试其抗腐蚀性能,并用扫描电镜观察合金腐蚀前后表面形貌的变化。结果各代试样间Ecorr、Ep、Rp、Icorr等电化学参数间差异无统计学意义(P>0.05);两两比较表明,Ⅱ代Ep大于Ⅰ代(P=0.023),余差异无统计学意义;扫描电镜观察,极化扫描后试样表面产生腐蚀,但各代之间没有明显区别。结论镍铬烤瓷合金经反复熔铸5次后电化学腐蚀没有明显改变。

Objective To investigate the influence of recasting on the electrochemical corrosion properties of the Ni-Cr alloy for porcelain-fused-to-metal restoration in artificial saliva. Methods Five groups of cylindrical specimens [（qb=（4.02 ± 0.04）mm,l=（8.00 ± 0.07）mm] were made by casting Ni- Cr alloys for porcelain-fused-to-metal restoration successively for 1, 2, 3, 4 and 5 times （Generation Ⅰ -Ⅴ ）, respectively. One undersurface of the specimen was polished using standard metallurgical procedures with wet aluminum oxide papers, the other undersurface was welded with copper wires. The specimens were embeded with polymethyl methacrylate with the testing surfaces exposed. The electrochemical corrosion behavior of the recasted Ni-Cr alloys was studied by potentiodynamic polarization in artificial saliva [t=（37.0 ± 1.0）℃ ,pH=7.4 ±0.1] according to ISO 10271 （2001） to measure the corrosion potential （Eeorr）, breakdown potential （Ep）, polarization resistance （Rp） and self-corrosion current density （Icorr）. The surface characteristics of the specimens were observed after test by scanning electron microscope. The experimental data were analysed by One-way ANOVA and Dunnett-t test. Results It was found that varieties of five generations of specimen in Ecorr, Ep, Rp, Icorr have no statistical significant differences （P 〉 0.05）. Dunnett-t test demonstrates that there were no differenced except that Ep of lI was greater than I （P=0.23）. Pitting corrosion on the alloy surface showed no differences among the five groups. Conclusion Ni-Cr casting alloy for porcelain-fused-tometal restoration can be reused after five times remelting in term of electrochemical corrosion.