高溫腐蝕
( 1. 北京科技大學 材料科學與工程學院， 北京 100083；
2. 寧夏大學 物理系， 銀川 750021；
3. Special Metals Corporation, Huntington, WV 25705, USA)
摘 要: 利用XRD， SEM和EDS等實驗技術研究了一種新的超級超臨界鍋爐過熱器管材Ni-Cr-Co基高溫合金在模擬煤燃燒環(huán)境中的高溫腐蝕行為。合金在700℃遭受的腐蝕過程分為2個階段。 在初始階段， 合金發(fā)生了氧化和硫化腐蝕，表面形成了保護性的Cr2O3膜，同時出現(xiàn)了內(nèi)硫化現(xiàn)象。 在加速腐蝕階段， 因CoSO4熔鹽在合金表面的穩(wěn)定存在使合金遭受嚴重的低溫熱腐蝕。當處于較高的SO3分壓時，鈷或氧化鈷在合金表面熔鹽中的溶解是造成合金抗腐蝕性能退化的原因。
關鍵字: Ni-Cr-Co基高溫合金；合成煤灰/煙氣； 低溫熱腐蝕；腐蝕機理
（ 1. School of Materials Science and Engineering,
University of Science and Technology Beijing,
Beijing 100083, China;
2. Department of Physics, Ningxia University,
Yinchuan 750021, China;
3. Special Metals Corporation, Huntington, WV 25705, USA）
Abstract: High temperature corrosion behavior of a new Ni-Cr-Co base superalloy, which is expected to serve as the material for the superheater/reheater tube in the ultra-supercritical boilers, was investigated in a laboratory-simulated coal-fired condition by means of XRD, SEM and EDS. The corrosion can be generally divided into two stages. The first one is an initial stage, during which a combination of oxidation and sulfidation occurr at the mean time, and the protective Cr2O3 scale forms on the surface and the internal sulfide appears. The second is an accelerated stage, during which severe low temperature hot corrosion happens due to the presence of the molten CoSO4. The rapid degradation of corrosion resistance of alloy is attributed to the dissolution of both cobalt and cobalt oxide on the surface at high SO3 levels.
Key words: Ni-Cr-Co base superalloy; synthetic coal ash/flue gas; low temperature hot corrosion; corrosion mechanism
