Development of High corrosion - resistant Materials for Advanced Waste Incineration Plants

本研究的目的是开发用于先进垃圾焚烧厂废气热交换的高耐腐蚀材料。由于能够耐受废气环境的金属材料仅限于Ni基合金，因此制备了纯Ni、二元Ni-Cr合金和含有Mo或Si的三元Ni-Cr合金作为样品材料。研究了这些材料在模拟废气环境中的热腐蚀行为。最后给出了高耐蚀合金的化学成分。主要研究结果如下：1.在试样表面镀覆Na_2SO_4-NaCl-KCl熔盐涂层，显著提高了纯Ni、Ni-Cr和Ni-Cr-（Si，Mo）合金的氧化增重.在1173 K高温氧气气氛中加入微量HCl，抑制了纯Ni的氧化，但加速了Ni-Cr合金的氧化.在镍中添加铬可降低试样在氧气、含氧HCl和含氧HCl与水蒸气中熔盐涂层下的氧化增重。在这种情况下，形成了由Cr_2O_3组成的连续致密的氧化膜.在Ni-10mass%Cr合金中加入Si或Mo，可降低合金在含氧HCl气氛中熔盐涂层下的氧化增重。结果表明，含铬量高的二元Ni-Cr合金和三元Ni-Cr-（Mo，Si）合金适合作为先进垃圾焚烧厂废气换热的高耐蚀材料。

The object of this study was the development of high corrosion-resistant materials for the heat exchange of the exhaust gas in the advanced waste incineration plants. As the metallic materials, which can be resistant to the exhaust gas environment, are limited to Ni-base alloys, pure Ni, binary Ni-Cr alloys, and ternary Ni-Cr alloys containing Mo or Si were prepared as the sample materials. The hot corrosion behavior of these materials in the exhaust gas-imitative environment was investigated. Finally, the chemical composition of alloy having high corrosion-resistant was showed. The obtained results were as follows:1. The coating of molten Na_2SO_4-NaCI-KCI on the specimen extremely increased the mass gain due to oxidation of pure Ni, Ni-Cr and Ni-Cr-(Si, Mo) alloy.2. The addition of trace amount of HCI into the oxygen atmosphere at high temperature of 1173 K inhibited the oxidation of pure Ni, while that accelerated the oxidation of Ni-Cr alloy.3. The addition of chromium into nickel decreased the mass gain due to oxidation under the coating of molten salt on the specimen in oxygen, oxygen containing HCI and oxygen containing HCI and water vapor. For this case, the formation of a continuous and dense scale consisting of Cr_2O_3 was observed.4. The addition of silicon or molybdenum into Ni-10mass% Cr alloy decreased the mass gain due to oxidation of the alloys under the coating of molten salt on the specimen in oxygen containing HCI atmosphere. For the case, the formation of a dense layer consisting of Cr_2O_3 at the interior side of the scale was observed.Consequently, it was found from the above results that the binary Ni-Cr alloys containing high amount of chromium and the ternary Ni-Cr-(Mo, Si) alloys was suitable as the high corrosion-resistant material for the heat exchange of the exhaust gas in the advanced waste incineration plants.