The cast structures influencing the electrochemical corrosion behavior of Co-Cr and Ni-Cr dental alloys were studied using potentiodynamic polarization and AC impedance in 0.9% (mass fraction) NaCl solution at (37...The cast structures influencing the electrochemical corrosion behavior of Co-Cr and Ni-Cr dental alloys were studied using potentiodynamic polarization and AC impedance in 0.9% (mass fraction) NaCl solution at (37±1) ℃. The phase and microstructure of the alloys that were fabricated using two different casting methods viz. centrifugal casting and high frequency induction casting, were examined using X-ray diffraction analysis, scanning electron microscopy and energy dispersive spectroscopy. The roles of alloying elements and the passive film homogeneity on the corrosion resistance of Co-Cr-Mo and Ni-Cr-Mo dental cast alloys were reviewed. The results of electrochemical study show that the dependence of corrosion resistance on the microstructure associated with the casting methods is marginal. The Co-Cr alloy exhibits more desirable corrosion resistance properties than the Ni-Cr alloy. There is severe preferential dissolution of Ni-rich, Cr and Mo depleted zones in the Ni-Cr alloy.展开更多
目的:观察4种金属铸造冠磁共振成像(MRI)检查时所产生金属伪影。方法:给实验犬依次佩戴钴铬合金、低钛合金、镍铬合金、纯钛4种试验铸造冠(右上第二前磨牙),分别进行常规3.0 T 6个序列及1.5 T 4个序列磁共振头部扫描,测量4种铸造冠所产...目的:观察4种金属铸造冠磁共振成像(MRI)检查时所产生金属伪影。方法:给实验犬依次佩戴钴铬合金、低钛合金、镍铬合金、纯钛4种试验铸造冠(右上第二前磨牙),分别进行常规3.0 T 6个序列及1.5 T 4个序列磁共振头部扫描,测量4种铸造冠所产生的伪影的最大面积和伪影涉及图像的层数。结果:2种场强下钴铬合金铸造冠所产生的伪影面积最大(P<0.01);1.5 T场强下其他3种合金冠之间差异均无显著性(P>0.05);3.0 T场强下镍铬合金冠伪影大于低钛合金冠和纯钛冠(P<0.05);低钛合金冠与纯钛冠差异无显著性(P>0.05)。在2种场强下和全部扫描序列中,伪影涉及的图像层数均以钴铬合金冠的最多,纯钛金属冠最少,其余2种合金冠相同。结论:钴铬合金伪影程度最大,镍铬合金和低钛合金次之,纯钛在4种金属中伪影程度最小。展开更多
文摘The cast structures influencing the electrochemical corrosion behavior of Co-Cr and Ni-Cr dental alloys were studied using potentiodynamic polarization and AC impedance in 0.9% (mass fraction) NaCl solution at (37±1) ℃. The phase and microstructure of the alloys that were fabricated using two different casting methods viz. centrifugal casting and high frequency induction casting, were examined using X-ray diffraction analysis, scanning electron microscopy and energy dispersive spectroscopy. The roles of alloying elements and the passive film homogeneity on the corrosion resistance of Co-Cr-Mo and Ni-Cr-Mo dental cast alloys were reviewed. The results of electrochemical study show that the dependence of corrosion resistance on the microstructure associated with the casting methods is marginal. The Co-Cr alloy exhibits more desirable corrosion resistance properties than the Ni-Cr alloy. There is severe preferential dissolution of Ni-rich, Cr and Mo depleted zones in the Ni-Cr alloy.
文摘目的:观察4种金属铸造冠磁共振成像(MRI)检查时所产生金属伪影。方法:给实验犬依次佩戴钴铬合金、低钛合金、镍铬合金、纯钛4种试验铸造冠(右上第二前磨牙),分别进行常规3.0 T 6个序列及1.5 T 4个序列磁共振头部扫描,测量4种铸造冠所产生的伪影的最大面积和伪影涉及图像的层数。结果:2种场强下钴铬合金铸造冠所产生的伪影面积最大(P<0.01);1.5 T场强下其他3种合金冠之间差异均无显著性(P>0.05);3.0 T场强下镍铬合金冠伪影大于低钛合金冠和纯钛冠(P<0.05);低钛合金冠与纯钛冠差异无显著性(P>0.05)。在2种场强下和全部扫描序列中,伪影涉及的图像层数均以钴铬合金冠的最多,纯钛金属冠最少,其余2种合金冠相同。结论:钴铬合金伪影程度最大,镍铬合金和低钛合金次之,纯钛在4种金属中伪影程度最小。