【作者】 鲍艳东；

【导师】 苏义祥；

【作者基本信息】 兰州理工大学 ， 材料加工工程， 2011， 硕士

【摘要】 课题组开发研制的新型Te-Ni-Cr合金材料是一种优秀的耐磨、耐蚀材料。本文就元素Te对镍铬合金的耐腐蚀性及腐蚀行为的影响进行了初步研究。运用金相显微观察、X射线衍射、背散射观察、显微硬度检测及摩擦磨损检测等手段研究了添加Te元素的新型合金的显微组织结构及机械性能的变化。结果表明:加入碲的合金,金相组织中出现了黑色的突起相,这种相牢牢地镶嵌在基体表面。新型碲镍铬合金的相由基体α-Ni3CrFe相,β-Cr5Ni2FeB相,γ-C19Cr7Mo24相组成,添加碲元素后促使合金析出β相、γ相。材料的显微硬度有了很大的提高,耐摩擦性加强,摩擦系数随时间变化稳定。碲的加入使材料的显微结构发生变化,材料的机械性能有了很大的改善。通过静态浸泡腐蚀试验、扫描电镜（SEM）、X射线衍射、能谱分析等手段研究了Te含量不同的新型合金在海水（3.5%NaCl溶液）、5%H₂SO₄溶液中的耐腐蚀性及腐蚀行为。结果表明:碲镍铬合金在海水、5%H₂SO₄溶液中均具有很好的耐腐蚀性。碲加强了材料耐腐蚀性。当加入0.8%Te时,材料在海水、5%H₂SO₄溶液中的耐腐蚀性达到最好。Te-Ni-Cr合金在静态水溶液中发生电化学腐蚀,在海水中的腐蚀形态为点蚀,加碲合金比未加碲合金的腐蚀坑小且内壁较光滑,腐蚀产物排布较致密,与基体结合较紧密,抵抗材料进一步腐蚀的能力较强;在5%H₂SO₄溶液中,材料的耐腐蚀性较在海水中要好,一般腐蚀是围绕合金表面的缺陷处开始进行的。在海水中合金的腐蚀产物是镍和铁的氧化物的混合物,在5% H₂SO₄溶液中的腐蚀产物是镍的氧化物,铬、铁的硫化物及氧化物。高温熔盐腐蚀实验是将含Te质量分数为0.8%的碲镍铬合金试样置于750℃Na₂SO₄-25%NaCl高温熔盐中等温加热腐蚀3 h、6 h、12 h、18 h、24 h、30 h。实验结果表明,碲镍铬合金在开始腐蚀阶段是耐蚀的,随着时间的延长,腐蚀加剧,材料的耐腐蚀性失效。在腐蚀3 h、18 h、30 h这三个时间段内,合金表面都有Ni₂S₃、Fe₂O₃、Cr₂O₃腐蚀产物生成。18 h时出现NiS、CrS。30 h的时候出现NiS₂、Cr₂S₃。合金的热腐蚀是一个硫化—氧化共存的过程。碲镍铬合金在熔盐中开始腐蚀阶段,腐蚀产物能够较牢固的和基体连接在一起,随着腐蚀时间的延长,产物增多形成腐蚀层,腐蚀时间继续延长,腐蚀层将从基体上脱落下来,然后新一轮腐蚀层的形成开始。更多还原

【Abstract】 The New Type of Te- Ni-Cr Alloy is an excellent corrosion resistant and wear resistance alloy which was developed by the researchers in our laboratory. This article probes into the influence of Te on the corrosion resistance and corrosion behavior of the New Type of Te- Ni-Cr Alloy.Microstructure and mechanical properties of New Type of Te- Ni-Cr Alloy samples with different mass fraction of Te were observed and analyzed by MEF3,X-ray diffraction, backscatter observation, microhardness testing and wear resistance,etc. The results indicated that:there is black protuberant phase in microstructure of the alloy with tellurium, , which are firmly embedded in the surface of the matrix. The New Type of Te- Ni-Cr Alloy phases compriseα-Ni3CrFe as matrix phase,β-Cr₅Ni₂FeB phase,γ-C₁₉Cr₇Mo₂₄phase,adding Te elements prompted alloy exhalationβphase,γphase.And micro hardness of material has been greatly improved,wear resistance,friction coefficient to strengthen stable over time.The Microscropic structure of the alloy with tellurium has been changed,mechanical properties have been greatly improved.The corrosion resistance and behavior of the New Type of Te- Ni-Cr Alloy with different mass fraction of Te element in seawater（3.5%NaCl solution）and 5%H₂SO₄ solution were investigated by using Static Immersing Corrosion test,scanning electron microscope （SEM）, XRD,EPMA,etc. The results show that the corrosion resistance of New Type of Te- Ni-Cr Alloy is very good in seawater and 5%H₂SO₄ solution. Because of anding tellurium, the corrosion resistance becomes strengthened. When anding 0.8% Te, the corrosion resistance is the best in seawater, 5% H₂SO₄ solution. Te - Ni - Cr alloy happenes electrochemical corrosion in solution, corrosion form a pit, pitting corrosion, the corrosion pit of adding tellurium alloy is smaller,wall is smoother and organizations are denser than didn’t add tellurium alloy. The ability to resist materials suffering further corrosion becomes stronger. In seawater, the corrosion products are nickel and iron oxide mixture. In 5% H₂SO₄ solution, the corrosion products are nickel ferrochrome sulfide and their oxides.High temperature molten salt corrosion experiment is that Te- Ni-Cr Alloy samples with mass fraction of Te 0.8% are corroded in 750℃Na2SO4- 25%NaCl, the corrosion time is 3 h, 6 h, 12 h, 18 h, 24 h, 30 h. The experimental results show that, at the start stage, Te- Ni-Cr Alloy is corrosion resistant , with the extension of time, the corrosion intensify, the corrosion resistance failure. In 3 h, 18 h, 30 h three stages, Ni₂S₃, Fe₂O₃, Cr₂O₃ corrosion products are generated in alloy surface. After 18 h, NiS、CrS occur. When 30 h, NiS₂、 Cr₂S₃ occur. Alloy heat corrosion is a vulcanizing - oxidation coexistence process. In the starte corrosion stage in plasma-nitriding on Te- Ni-Cr Alloy, the corrosion products can fairly solid connected together with substrate,with the corrosion time extension, increased corrosion layer formed product, time continue to increase, the corrosion layer off from substrate.更多还原