牙科用铬合金在不同pH值的人工唾液中耐腐蚀性能的研究

目的在模拟口腔环境下,研究牙科用铬合金（钴铬合金和镍铬合金）在pH值为7和5的人工唾液中的电化学腐蚀行为。方法用动电位极化曲线法,测定铬合金在pH值为7和5的人工唾液中自腐蚀电位、自腐蚀电流密度,与含钛元素镍铬合金进行比较分析;并用电化学阻抗谱研究铬合金的腐蚀机制和耐腐蚀性能。结果钴铬合金的自腐蚀电流密度低于含钛元素镍铬合金和镍铬合金,阻抗值高于含钛元素镍铬合金和镍铬合金;而镍铬合金自腐蚀电流密度高于含钛元素镍铬合金,阻抗值略低于含钛元素镍铬合金。随pH值下降,合金表面自腐蚀电流密度均升高,阻抗值均降低,但钴铬合金的变化幅度最小。结论钴铬合金的耐腐蚀性能优于镍铬合金和含钛元素镍铬合金;随pH值下降,合金耐腐蚀性能均发生不同程度的下降。     

不同pH值与氟离子浓度对口腔常用金属修复材料电化学腐蚀的影响

目的 研究不同pH值与不同浓度氟离子(F-)对HBIC种植体和常用的四种冠修复金属材料在人工唾液中电化学腐蚀的影响.方法 将5种口腔常用金属,金合金(Au)、镍铬合金(NiCr)、钴铬合金(CoCr)、铸造纯钛(Ti)、HBIC种植钛材(H-Ti)分别置于不同pH值与含和不含F-的人工唾液中,采用动电位极化曲线法测得其自腐蚀电位和自腐蚀电流密度,分析材料的耐腐蚀性.结果 金合金、钴铬合金、镍铬合金的腐蚀电流密度随着H+的浓度增加而变大,差异有统计学意义(P<0.05),铸造纯钛及种植钛材在酸性含氟人工唾液中的腐蚀电流密度和自腐蚀电位变化明显,差异有统计学意义(P<0.05),F-对金合金的耐腐蚀性影响不明显.结论 pH的改变以及含氟环境会加剧种植体及其常用上部冠修复材料的电化学腐蚀性,金合金与纯钛的耐腐蚀性能较强.     

三种口腔铸造合金耐蚀性及表面氧化膜的比较

目的 探讨3种常用口腔铸造合金模拟烤瓷前后的耐蚀性差异及氧化膜成分,以期为临床合理选择非贵金属合金提供依据.方法 用电感耦合等离子体原子发射光谱法(inductively coupled plasma atomic emission spectroscopy,ICP-AES)检测模拟烤瓷前后3种常用烤瓷非贵金属合金(镍铬合金、钴铬合金、镍钛合金)在达尔伯克改良伊格尔培养液中浸泡30 d后离子析出的种类和含量.同时用X射线光电子能谱(X-ray photoelectron spectroscopy,XPS)对模拟烤瓷后合金表面生成的氧化膜进行分析,扫描电镜(SEM)对合金表面腐蚀形态进行观察.结果 模拟烤瓷前3种合金离子总质量浓度由大到小依次为镍铬合金[(2.829±0.694)mg/L]、钴铬合金[(2.120±0.418)mg/L]、镍钛合金[(1.211±0.101)mg/L];镍铬合金组镍的质量浓度[(1.531±0.392)mg/L]＞镍钛合金组[(0.830±0.052)mg/L],钴和钼离子质量浓度由大到小为钴铬合金组[钴:(0.048±0.011)mg/L;钼:(1.562±0.333)mg/L]、镍铬合金组[钴:(0.034±0.002)mg/L;钼:(1.264±0.302)mg/L]、镍钛合金组[钴:(0.013±0.006)mg/L;钼:(0.151±0.026)mg/L],差异有统计学意义(P＜0.05).模拟烤瓷后3种合金离子析出总量[镍铬合金:(0.861±0.054)mg/L;钴铬合金:(0.695±0.327)mg/L;镍钛合金:(0.892±0.115)mg/L]均比未模拟烤瓷处理的合金离子析出总量少,差异有统计学意义(P＜0.05).XPS分析显示,模拟烤瓷后3种合金表面Cr2O3和钼、镍氧化物的含量增加.结论 3种常用烤瓷铸造合金中镍铬合金的离子析出量最大,耐蚀性最差;烤瓷加热处理可促进这3种合金生成连续的Cr2O3氧化膜,使合金的耐蚀性增强.

Abstract：

Objective To evaluate the types and compositions of oxide films formed during porcelain-fused-to-metal( PFM ) firing on three kinds of dental casting alloys, and to investigate the corrosion property of these alloys in Dulbecco's modification of Eagle's medium( DMEM ) cell culture fluid, before and after PFM firing. Methods Specimens of three dental casting alloys( Ni-Cr, Co-Cr and Ni-Ti) before and after PFM firing were prepared, and were immersed in DMEM cell culture fluid. After 30 days, the type and concentration of released metal ions were measured using inductively coupled plasma atomic emission spectroscopy(ICP-AES). X-ray photoelectron spectroscopy(XPS) and scanning electron microscope( SEM )were used for analysis of oxide film on the alloys. One way-ANOVA was adopted in data analysis. Results The total amount of metal ions released from the three dental alloys was found to be highest in Ni-Cr alloy [(2.829±0.694) mg/L], followed by Co-Cr[(2. 120 ±0.418) mg/L]and Ni-Ti alloy[(1.211 ±0. 101 ) mg/L]. The amount of Ni ions released from Ni-Cr alloys[( 1. 531 ± 0. 392) mg/L]was higher than that from Ni-Ti alloys[(0. 830 ±0. 052) mg/L]. The amount of Cr, Mo ions released from Co-Cr alloy [Cr: (0. 048 ± 0. 011 ) mg/L, Mo: ( 1. 562 ± 0. 333 ) mg/L]was higher than that from Ni-Cr alloy[Cr:(0. 034 ±0. 002) mg/L, Mo: ( 1. 264 ±0. 302) mg/L]and Ni-Ti alloy[Cr: (0. 013 ±0. 006) mg/L, Mo:(0. 151 ±0. 026) mg/L](P ＜0. 05). After PFM firing, the total amount of metal irons released from the three dental alloys decreased[N i-Cr: (0. 861 ± 0. 054 ) mg/L, Co-Cr: (0. 695 ± 0. 327 ) mg/L, Ni-Ti:(0. 892 ±0. 115) mg/L](P ＜ 0. 05). In addition, XPS showed increase of Cr2O3 and Mo-Ni oxide on the surface of all the alloys after PFM firing. Conclusions The amount of ions released from Ni-Cr alloy was the highest among the three dental casting alloys, this means Ni-Cr alloy is prone to corrode. The PFM firing process changed the alloys' surface composition. Increased Ni, Cr and Mo were found in oxide film, and the increase in Cr2O3 can improve the corrosion-resistance of alloys.     

齿科钴铬-镍铬合金激光焊接后耐腐蚀性评价

目的:研究激光焊接钴铬-镍铬合金的体外电化学行为及离子释出情况。方法:在体外模拟口腔环境中,测出激光焊接钴铬-镍铬合金阳极极化曲线及特征指数;检测激光焊接镍铬-钴铬合金在不同时间的离子释出情况,以钴铬合金、镍铬合金为对照。结果:钴铬合金自腐蚀电位低于镍铬合金,激光焊接钴铬-镍铬合金的自腐蚀电位、维钝电流密度、破裂电位介于前两者之间;激光焊接镍铬-钴铬合金,镍离子释出量7日后少于镍铬合金,钴离子释出量始终高于镍铬合金。结论:激光焊接钴铬-镍铬合金后,钴铬合金的阳极保护作用可减少镍铬合金镍离子释出,有助于改善镍铬合金生物相容性;激光焊接钴铬-镍铬合金,对其整体耐腐蚀性未有较大影响。     

氯离子浓度对牙科铬合金耐腐蚀性能的影响

目的 在人工唾液中氯离子浓度升高的条件下,用动电位极化曲线法研究镍铬合金、钴铬合金和含钛镍铬合金的耐腐蚀性能的变化。方法 测定三种铬合金在氯化钠浓度分别为0.9%、2%、3%的人工唾液中的自腐蚀电位、自腐蚀电流密度,对其进行比较分析。结果 随着氯离子浓度升高,三种铬合金的自腐蚀电流密度均增大,腐蚀速度加快。钴铬合金受氯化钠浓度的影响最小。结论 在高氯环境中,三种铬合金腐蚀性能均降低,但钴铬合金耐腐蚀能力相对较强,这将影响它们的使用寿命。     

纳米非晶金刚石膜镀覆对镍铬及钴铬烤瓷合金离子析出的影响

目的：观测纳米非晶金刚石膜对镍铬及钴铬两种非贵金属烤瓷合金在人工唾液中金属离子析出的影响。方法：制备镍铬合金、钴铬合金圆片形试件各24个,镍铬及钴铬合金试件随机分成a1、b1及a2、b2各两组,a1、a2组试件表面不镀膜,b1、b2组试件表面完整镀膜膜厚60nm,将a1、a2、b1、b2每组试件平分两半,分别置于pH值为6.8和4.0的人工唾液中浸泡7天,检测各组试件的金属离子析出量。结果：a1、a2组试件在两种人工唾液中表现出其所含各种金属离子的析出,在pH=4酸性人工唾液中浸泡后的离子析出量显著高于其在pH=6.8中性人工唾液中浸泡后的离子析出量（P〈0.05）;b1、b2组试件在两种人工唾液中浸泡后,其离子析出量分别比a1、a2组试件显著降低（P〈0.01）。结论：镍铬合金、钴铬合金在中性和酸性人工唾液中表现出其所含各种金属离子的析出,在酸性人工唾液中其金属离子析出量显著增加;纳米非晶金刚石镀膜能显著降低镍铬、钴铬合金在中性和酸性人工唾液中的金属离子析出量,有良好的耐腐蚀性。     

五种全冠合金铸造后的腐蚀性研究

目的 测定五种制作全冠的合金铸造后在体外细胞培养液中析出金属离子的种类及不同时间段析出的各种金属离子的量。方法 本实验用电感藕荷等离子质谱仪（ICP－MS）定量测定金属离子测试。结果 镍铬合金和钴铬合金析出离子最多银钯合金和钯合金有一定的金属离子析出，纯钛只析出微量钛离子。结论 纯钛、钯合金的耐腐蚀性最好，银钯合金次之，镍铬合金和钴铬合金的耐腐蚀性较差。     

Corrosion behaviour and surface analysis of a Co-Cr and two Ni-Cr dental alloys before and after simulated porcelain firing

This study evaluated the corrosion behaviour and surface properties of a commercial cobalt-chromium (Co-Cr) alloy and two nickel-chromium (Ni-Cr) alloys [beryllium (Be)-free and Be-containing] before and after a simulated porcelain-firing process. Before porcelain firing, the microstructure, surface composition and hardness, electrochemical corrosion properties, and metal-ion release of as-cast alloy specimens were examined. After firing, similar alloy specimens were examined for the same properties. In both as-cast and fired conditions, the Co-Cr alloy (Wirobond C) showed significantly more resistance to corrosion than the two Ni-Cr alloys. After firing, the corrosion rate of the Be-free Ni-Cr alloy (Stellite N9) increased significantly, which corresponded to a reduction in the levels of Cr, molybdenum (Mo), and Ni in the surface oxides and to a reduction in the thickness of the surface oxide film. The corrosion properties of the Co-Cr alloy and the Be-containing Ni-Cr alloy (ChangPing) were not significantly affected by the firing process. Porcelain firing also changed the microstructure and microhardness values of the alloys, and there were increases in the release of Co and Ni ions, especially for Ni from the Be-free Ni-Cr alloy. Thus, the corrosion rate of the Be-free Ni-Cr alloy increased significantly after porcelain firing, whereas the firing process had little effect on the corrosion susceptibility of the Co-Cr alloy and the Be-containing Ni-Cr alloy.     

表没食子儿茶素没食子酸酯对镍铬合金电化学腐蚀后表面结构和性能的影响

目的:研究表没食子儿茶素没食子酸酯(epigallocatechin gallate, EGCG)对镍铬合金电化学腐蚀后表面结构和性能的影响。方法:采用体视显微镜和扫描电镜,观察经0 g/L和1.0 g/L EGCG人工唾液电化学腐蚀后镍铬合金的表面形貌,并运用光电子能谱仪分析经0 g/L和1.0 g/L EGCG人工唾液电化学腐蚀后镍铬合金的表面腐蚀产物。结果:经0 g/L和1.0 g/L EGCG人工唾液电化学腐蚀后,镍铬合金表面均有不同程度的腐蚀,在0 g/L EGCG人工唾液中,出现的点蚀坑直径较小,基本未影响合金表面的枝晶结构;而在1.0 g/L EGCG人工唾液中,镍铬合金表面发生了较为严重的腐蚀,点蚀坑直径较大,枝晶区间开始融合、变得模糊不清。此外,经0 g/L EGCG和1.0 g/L EGCG人工唾液电化学腐蚀后,镍铬合金表面溅射120 s后均检测到了O、Ni、Cr、Be、C及Mo元素,表面氧化物均主要为NiO和Cr2O3。与0 g/L EGCG人工唾液相比,镍铬合金在1.0 g/L EGCG人工唾液电化学腐蚀后表面O元素、NiO和Cr2O3的含量较低。结论:经EGCG人工唾液电化学腐蚀后,镍铬合金表面形貌和表面腐蚀产物结果一致,提示1.0 g/L EGCG促使镍铬合金表面耐腐蚀性能变差,表面腐蚀产物中氧化物含量也降低。     

3种牙科铸造金属模拟唾液浸泡后粗糙度的变化

目的：通过考察钴铬合金、镍铬合金以及纯钛在不同pH值人工唾液中浸泡后表面粗糙度的变化，研究3种常用牙科金属的耐腐蚀能力。方法：将3种金属的标准铸造试件逐级打磨抛光后。浸泡于pH值分别为7．0和5．6的人工唾液中。3个月后检测试件表面粗糙度，并用金相显微镜观察试件表面。采用SPSS11．0软件包对数据进行单因素方差分析及t检验。结果：pH=5．6的人工唾液浸泡后，3种材料表面粗糙度有显著差异，镍铬合金〉钴铬合金〉纯钛金属（P〈0．01）。pH=7．0的人工唾液浸泡后，镍铬合金表面粗糙度大于钴铬合金和纯钛（P〈0．01），但钴铬合金和纯钛之间无统计学差异（p〉0．05）。pH=5．6人工唾液浸泡组的镍铬合金和钴铬合金表面粗糙度大于pH=7．0组的同种材料（P〈0．01）。各试验组表面粗糙度大小与显微镜观察到的材料表面腐蚀程度一致。结论：纯钛在酸性和中性环境下均有较强的耐腐蚀性，钴铬合金、镍铬合金在酸性介质中的耐腐蚀性较差。3种金属的耐腐蚀性由大到小排列为：纯钛金属〉钴铬合金〉镍铬合金。     

In vitro corrosion characteristics of commercially available orthodontic wires

The corrosion characteristics of orthodontic alloy wires were investigated both in as-received and grinded conditions in 0.9% NaCl solution by atomic absorption spectrophotometry and potentiodynamic polarization measurements. The amount of each metal ion released from most alloys was larger for the grinded wires than for the as-received wires (p<0.01). The fact that the beta-Ti alloy wire (Ti-Mo-Zr) does not contain allergenic metals such as Ni, Co, and Cr, and the finding that resistance to both general and localized corrosion is the highest among the six wires investigated suggest that this wire is the most biocompatible orthodontic wire. Since a small amount of Ni, Cr or Co ions were released from Ni-Ti, Co-Cr and stainless steel wires, special attention should be paid during their clinical use for patients with allergic tendencies.     

牙科低贵合金腐蚀后表面成分分析

目的 通过分析牙科低贵合金腐蚀后的表面成份，探讨腐蚀机理。方法 运用静态浸泡试验评价Ag-Pd合金的腐蚀性能并与常用牙科修复合金Co-Cr、Cu-Al比较。腐蚀介质为Fusayama人工唾液（37℃，pH=5)。采用扫描电镜、电子能谱分析腐蚀产物。结果 铜铝合金的腐蚀大于银钯合金和钴铬合金（P＜0.05)；银钯合金主要以银和铜腐蚀为主，铜选择性释出。结论 低贵合金的腐蚀源于多相结构之间电位差引起的原电池反应。     

Effect of (-)-epigallocatechin gallate on electrochemical behavior and surface film composition of Co-Cr alloy used in dental restorations

The aim of this study was to investigate the electrochemical behavior of Co-Cr alloy in artificial saliva containing (-)-epigallocatechin gallate (EGCG) and to characterize the composition and structure of the passive film formed by potentiodynamic polarization.Electrochemical measurements ranked the corrosion resistance of Co-Cr dental cast alloy as follows when exposed to artifi cial saliva containing different concentrations of EGCG: 4.0 g/L<2.0 g/L<0 g/L<0.5 g/L<1.0 g/L. This showed that the concentration of EGCG in artificial saliva affected the corrosion behavior of Co-Cr alloy. X-ray photoelectron spectroscopy (XPS) results revealed that theoutermost surface layer on Co-Cr alloy was mainly composed of Cr2O3 and EGCG-Cr (III) ion complex, which were formed by redoxand complex formation reactions respectively. When the redox reaction was dominant, Co-Cr alloy exhibited high corrosion resistancein EGCG-containing artificial saliva. On the contrary, when the complex formation reaction was dominant, Co-Cr alloy exhibited low corrosion resistance.     

Corrosion by galvanic coupling between amalgam and different chromium-based alloys.

OBJECTIVES: In recent years there has been an increase in the use of dental casting alloys in prosthodontic treatment. Many patients have metals or alloys, as well as amalgam fillings, in their mouth, and will have them for many years. The aim of this study was to evaluate and compare, in vitro, the galvanic corrosion behavior of chromium-cobalt alloy (Remanium GM 380) and chromium-nickel alloy (Remanium CS) when bound together or coupled with silver-based amalgam (Amalcap plus). METHODS: An electrochemical characterization of the alloys was performed by potentiostatic and potentiodynamic methods, i.e. the open circuit potential (OCP), the corrosion potential (E(CORR)), corrosion current density (i(CORR)) and corrosion resistance (R(P)). The electromotive force (EMF) of the bimetallic cells was also tested. Electroanalytical techniques were used to estimate the release of any respective element from the dental alloys under study into the artificial saliva solution. RESULTS: It was found that a bimetallic cell consisting of Remanium CS and Remanium GM 380 alloys has a very low EMF (a few mV) and is not a potential source of galvanic currents in the oral cavity. However, galvanic cells prepared from Amalcap plus and Remanium CS or Remanium GM 380 showed a much greater EMF: 104 and 109mV, respectively. This clearly indicates that in these latter cases it is possible to expect some metal ions in the saliva solution as a result of the work of galvanic currents. It was found, by adsorptive stripping voltammetry analysis, that nickel or cobalt, depending on the alloy used, appeared in the saliva solution and increased in concentration over time. SIGNIFICANCE: The results indicate that the correct design and use of dental alloys are important when determining the appropriate treatment for a specific patient.     

Corrosion of nickel-based dental casting alloys.

OBJECTIVES: To study the microstructure, corrosion behaviour and cell culture response of two nickel-based dental casting alloys before and after a heat treatment to simulate porcelain firing. METHODS: The microstructure was studied using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Corrosion behaviour was evaluated by electrochemical measurements in artificial saliva at different values of pH in the presence of a crevice. 3T3 mouse fibroblasts were exposed indirectly to alloy specimens and the number of viable cells counted after 3 and 6 days compared to a control culture. RESULTS: Small changes in microstructure were observed after heat treatment but had a negligible effect on the corrosion properties in the conditions tested. The alloy with a lower bulk level of Cr (12.6 wt.%) showed lower corrosion resistance, indicated by an increased passive current density and this stability was greatly reduced at pH 2.5, where crevice corrosion was observed. Selective dissolution occurred at regions within the microstructure containing lower levels of Cr and Mo. Furthermore, the proliferation of 3T3 mouse fibroblasts was reduced (p<0.05) when exposed indirectly to this alloy. The alloy containing a higher level of Cr (25 wt.%) showed superior corrosion resistance, which was associated with a more uniform distribution of Cr in the alloy microstructure. SIGNIFICANCE: The presence of crevices combined with an inhomogeneous distribution of Cr in the microstructure can lead to accelerated corrosion of Ni-based alloys with lower Cr contents. This effect can be avoided by increasing the Cr content of the alloy.     

软磁合金与4 种齿科合金间电偶腐蚀的浸泡实验研究

目的:评价铁铬钼软磁合金与4种口腔常用合金在模拟口腔环境中的电偶腐蚀性能。方法:Fe-16Cr-2Mo软磁合金分别与钛75合金、TA2型纯钛、Co-Cr合金、Ni-Cr烤瓷合金组成的4组电偶对在人工唾液中浸泡6个月后,以原子吸收光谱仪测定每组电偶对浸泡液中溶出的金属离子浓度。结果:4组电偶对中析出的离子量与对照组相比均无显著差异(P>0.05)。结论:铁铬钼软磁合金在口腔环境中与牙科常用合金间可以认为不会有电偶腐蚀发生。     

Long-term corrosion studies in vitro of gold, cobalt-chromium, and nickel-chromium alloys in contact

Specimens of various types of dental casting alloys were stored in phosphate-buffered 0.9% NaCl solution for 35 weeks. Every 7 weeks the solutions were changed and analyzed with regard to elements released from the alloys. The release of Cu from type III gold alloy increased in contact with gold alloys for metallo-ceramic use in a 1:2 area relation. However, when the area relation was reversed, no difference in the amounts of elements released was observed. Crevice corrosion was initiated with one of the Co-Cr alloys in contact with type III gold alloy. The crevice corrosion increased the amounts of Co and Cr released into the solutions. The release of Ni and Cr from the Ni-Cr alloys was prominent. These alloys were very susceptible to crevice corrosion. With one of the Ni-Cr alloys the release of elements increased in contact with type III gold alloy.     

The electrochemical behavior and surface analysis of Ti50Ni47.2Co2.8 alloy for orthodontic use

OBJECTIVES: The aim of this study was to investigate the electrochemical behavior of Ti50Ni47.2Co2.8 alloy in deaerated artificial saliva solutions with binary NiTi alloy as reference and to characterize the composition and structure of the passive film after polarization tests. METHODS: The corrosion behavior of NiTiCo alloy was systematically studied by open circuit potential, potentiodynamic and potentiostatic techniques. The surface characterization after anodic polarization tests were demonstrated by XPS. The electrolytes were maintained at 37 degrees C by immersing the test cell in water bath. 500 mV vs. SCE was applied on the samples for potentiostatic tests. The metal ions concentration was measured by ICP/OES. RESULTS: Potentiodynamic and potentiostatic tests results showed that the corrosion behavior of NiTiCo was similar to that of NiTi alloy. With the increase of pH value of the electrolytes, both corrosion potential (Ecorr) and pitting corrosion potential (Eb) decreased. XPS results revealed that the outmost passive film consisted mainly of TiO2 which were identical with that of NiTi alloy. The Ni ion release amount of NiTiCo was very close to that of NiTi alloy as examined by ICP/OES. Neither Ti nor Co ion was detected due to the detection limitation. SIGNIFICANCE: The corresponding relationship between corrosion behavior and pH value of the artificial saliva should be taken into consideration during the application of orthodontic wires. The addition of Co had little effect on the corrosion behavior of NiTi as well as the formation of the passive film.     

Study of the influence of the anodic potential on metal-components dissolution from dental alloys

This study aims to evaluate the influence of the anodic potential on metal-components dissolution from dental alloys and is intended to serve as an aid in the investigation of dental metal eruption (metal allergy). In the experiments, anodic potentials were applied electrochemically to various dental alloys in a 0.9% NaCl solution. Thereafter amounts of metal-component dissolution were measured by means of atomic absorption spectrophotometry. In addition, relations between metal-component dissolution and electrochemical characteristics (anodic polarization and charge transfer calculated from current density-time transients) were considered. Results: 1. Breakdown potentials determined on the basis of anodic polarization profiles agreed with potentials of remarkable increase in component dissolution. 2. Current density-time transients gave good indications of alloys' corrosion tendencies. Correlations between charge transfer and total amounts of metal-component dissolution were comparatively good. 3. Metal-component dissolutions in various alloys at fixed anodic potentials 1) Cu and Zn were found to dissolve slightly from gold alloys (types II and IV) at potentials above 200 mV (vs SCE). 2) Ag, Pd, Cu, and Zn were found to dissolve from the Ag-Pd-Cu-Au alloy at potentials above 100 mV. A comparatively large amount of Zn was released at low potentials. Amounts of Ag and Cu dissolution increased rapidly at 300 mV and 500 mV respectively. Although traces of it were detectable at low potentials, dissolution of Pd increased remarkably at 500 mV. 3) Ag, In, and Zn were found to dissolve from the Ag-In-Zn alloy at potentials above O mV. Amounts of In and Zn dissolution increased above 20 mV. The increase was especially remarkable in the case of In. 4) Sn and Zn were found to dissolve from the Ag-Sn-Zn alloy at potentials above -200 mV; Ag dissolved from the same alloy at potentials above 100 mV. Amounts of Sn and Zn dissolution increased at potentials above 100 mV. This was especially true in the case of Sn. 5) Ni, Cu and Si were found to dissolve from the soft type Ni-Cr alloy (9.0 wt% Cr) at potentials above -100 mV. Cr, Mn, and Fe dissolved from the same alloy at potentials above 0 mV; and Co at potentials above 200 mV. Metal-component dissolution was greater in the case of this alloy than in those of all the other alloys used in this study. A considerable amount fo Ni was released at 0 mV.(ABSTRACT TRUNCATED AT 400 WORDS)     

人工唾液中氯化钠浓度对钴铬、镍铬、含钛镍铬合金腐蚀行为的影响

目的：在人工唾液中氯化钠浓度升高的条件下,用电化学阻抗谱研究3种牙科常用合金（钴铬、镍铬、含钛镍铬合金）腐蚀行为的变化。方法：测定在人工唾液中氯化钠浓度分别为0.9%、2%、3%的条件下,3种合金的电化学阻抗谱,将各体系中合金界面电容和电荷转移电阻拟合,分析其腐蚀机制和耐腐蚀性能的变化。结果：随着氯化钠浓度升高,3种合金的界面电荷转移电阻（Rt值）都分别减小,界面电容（Qdl）增大,腐蚀反应过程加剧,抗蚀能力降低。但钴铬合金的Rt值是最大的。结论：在高氯环境中,3种合金腐蚀反应加快,抗腐蚀能力均降低,但钴铬合金抗腐蚀能力相对较强,这将影响它们的使用寿命。