Mizutani M
Department of Dental Materials Science, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan.
Aichi Gakuin Daigaku Shigakkai Shi. 1990 Mar;28(1 Pt 1):59-78.
The effects of Cr and Mo addition to Ni-Cr alloys on high temperature oxidation were investigated. The alloys were prepared with the composition of Cr ranging from 5 to 40 wt%. Also 2, 4 and 9 wt% of Mo was added to both Ni-5% Cr and Ni-20% Cr binary alloys. The alloys were heated at 800 degrees C, 900 degrees C and 1000 degrees C for 15 minutes in air, and the weight change after heat treatment was measured by electric automatic balance. The weight change during heating was measured by thermogravimetric measurement (TG). The products after heat treatment were characterized by X-ray diffraction and scanning electron microscopy (SEM). The results are summarized as follows: The Ni-Cr binary alloys were classified into three types of Cr ranging from 5 to 20 wt%, Cr 25% and Cr from 30 wt% to 40 wt% according to the weight gains with oxidation. In the case of the more than 25 wt% Cr content of the Ni-Cr binary alloys, the weight gain was extremely low and the heating temperature effects on the weight change were also small. X-ray diffraction study showed that NiO, NiCr2O4 and Cr2O3 formed on the surface of the Ni-Cr binary alloys whose composition of Cr ranged from 5 to 25 wt%, whereas NiO and NiCr2O4 rarely formed on the Ni-Cr binary alloys whose composition of Cr ranged from 30 to 40 wt%. This suggests that the formation of Cr2O3 prevents the formation of NiO on the alloy with a high Cr content. The weight gain of the Ni-Cr-Mo ternary alloys was smaller than that of the Ni-Cr binary alloys without Mo, and the temperature effects on the weight gain of the Ni-Cr-Mo ternary alloys were different for each Cr content. However, the effect of the amounts of Mo was small. NiO, NiCr2O4, Cr2O3 and MoO2 were identified by X-ray diffraction on the surface of the Ni-Cr-Mo ternary alloys. According to the SEM observation, it seems that NiO was formed at the outermost layer, both NiCr2O4 and Cr2O3 at the inside layer, and MoO2 at the innermost layer. The formation of both NiO and Cr2O3 on the Ni-Cr-Mo ternary alloys was restrained compared with that of the Ni-Cr binary alloys. However, the adhesion of oxides to the Ni-Cr-Mo ternary alloys was lower than that of the Ni-Cr binary alloys.
研究了向镍铬合金中添加铬和钼对高温氧化的影响。制备了铬含量在5 wt%至40 wt%范围内的合金。同时，在Ni-5%Cr和Ni-20%Cr二元合金中分别添加了2 wt%、4 wt%和9 wt%的钼。将合金在空气中于800℃、900℃和1000℃加热15分钟，通过电子自动天平测量热处理后的重量变化。通过热重测量（TG）测量加热过程中的重量变化。用X射线衍射和扫描电子显微镜（SEM）对热处理后的产物进行表征。结果总结如下：根据氧化增重情况，镍铬二元合金分为三种类型，铬含量分别为5 wt%至20 wt%、25 wt%以及30 wt%至40 wt%。对于铬含量超过25 wt%的镍铬二元合金，增重极低，加热温度对重量变化的影响也很小。X射线衍射研究表明，在铬含量为5 wt%至25 wt%的镍铬二元合金表面形成了NiO、NiCr2O4和Cr2O3，而在铬含量为30 wt%至40 wt%的镍铬二元合金表面很少形成NiO和NiCr2O4。这表明Cr2O3的形成阻止了高铬含量合金表面NiO的形成。镍铬钼三元合金的增重小于不含钼的镍铬二元合金，并且对于每种铬含量，温度对镍铬钼三元合金增重的影响各不相同。然而钼含量的影响较小。通过X射线衍射在镍铬钼三元合金表面鉴定出了NiO、NiCr2O4、Cr2O3和MoO2。根据SEM观察，似乎在最外层形成了NiO，在内层同时形成了NiCr2O4和Cr2O3，在最内层形成了MoO2。与镍铬二元合金相比，镍铬钼三元合金表面NiO和Cr2O3的形成受到抑制。然而，氧化物与镍铬钼三元合金的附着力低于镍铬二元合金。
