Improvement in Oxidation Resistance of Stainless Steel by Molten-Salt Electrodeposition of La

Improvement in the oxidation resistance of SUS304 stainless steel was accomplished by electrodeposition of La in a molten salt. The electrolysis of La was conducted using a potentiostatic-polarization method in an equimolar NaCl–KCl melt containing 3.5 mol. LaF ₃ at 1023 K. Observation of the specimen surface after polarization at –1.8 V (vs. Ag/Ag⁺ (0.1)) for 0.18 ks showed that La particles were uniformly dispersed on the surface. The oxidation resistance of the electrodeposited stainless steel was significantly improved as compared with the untreated stainless steel. The scale formed on the untreated stainless steel after oxidation was thick and consisted of Fe₂O₃ and Fe₃O₄, whereas the scale formed on the elecrodeposited stainless steel was extremely thin, and mainly consisted of Cr₂O₃.     

Structural evolution and superplastic formability of friction stir welded AA 2095 sheets

Friction stir welding was used to join superplastic AA 2095 sheets. The effect of welding rate on the grain size distribution and grain boundary misorientations in the stir zone was investigated. The superplastic behavior of the weld nugget parallel to the welding direction was also characterized at 495 °C and strain rates from 10⁻⁴s⁻¹ to 10⁻²s⁻¹. Increasing the welding rate during friction stir welding augmented the formation of a fine-equiaxed high-angle grain boundary structure within the stir zone. Increasing intensity of plastic straining during friction stir welding resulted in enhanced properties during subsequent superplastic formation. The maximum strain-to-failure was obtained for the weld made at a tool speed of 1000 rpm and a weld rate of 4.2 mm/s when tested at a superplastic forming strain rate of 10⁻³s⁻¹.     

Effects of lanthanum on properties of cathode materials and ion implanted spinning rings

The effects of rare earth elements on the structure of cathode materials composed of WC, 663Cu and Ti as well as the performances of spinning rings implanted with this cathode materials were investigated. The results show that rare earth elements can improve the microstructure and compactness of the cathode materials, and elevate the wear resistance and corrosion resistance of spinning rings implanted with these materials. Consequently, the yarn quality is improved significantly.     

Influence of chromizing treatment on the corrosion behavior of AISI 316 stainless steel in supercritical water oxidation

SCWO, sometimes referred to as hydrothermal waste processing, uses the solvating traits of water in its supercritical condition to effectively destroy liquid organic wastes. One major problem in the supercritical water oxidation process is corrosion, because all metallic tubes in the process are exposed to high temperature and high pressure as well as severe corrosive species such as Cl⁻, F⁻, S²⁻, and O²⁻. The presence of Cl⁻ when the pH of a solution is very low and the solution has excess oxygen causes active corrosion and metal loss by metal-chloride and/or oxychloride formation. This study performed a chromizing treatment on 316 stainless steel and immersion tests in supercritical water. Weight change of chromized steels and untreated steels was measured, and the chemical state and composition of oxide films on 316 stainless steel were investigated. On the basis of SCWO tests using distilled water, the oxide layer was found to be very thin and homogeneous and weight gain was observed regardless of testing temperature, while the chromizing treatment slightly reduced weight gain. In the case of SCWO tests using salt water, weight loss was observed regardless of testing temperature and its corrosion mode was pitting by chloride ion, while chromizing treatment greatly decreased the corrosion rate.     

Oxidation behaviour of the alloy IC-6 and protective coatings

In this work, NiCoCrAlY coatings were deposited on a new Ni-base alloy, IC-6. The oxidation kinetic curves of alloy IC-6, K17 and NiCoCrAlY coatings on alloy IC-6 at 900-1100 °C were obtained. The results indicated that the oxide scales consisted of α-Al₂O₃, NiAl₂O₄, NiO, as well as a small amount of NiMoO₄ and MoO₂. These scales occurred after alloy IC-6 exposure at 900 °C for 100 h. The weight loss occurred when alloy IC-6 were exposed at 1050 and 1100 °C due to the formation of volatile MoO₃. After the NiCoCrAlY coating was deposited, the scales mainly contained α-Al₂O₃, when the specimens were oxidized at 900 °C, and α-Al₂O₃and Cr₂O₃ at 1050 °C. The formation of α-Al₂O₃ and Cr₂O₃ scales on NiCoCrAlY coating was directly responsible for improving oxidation resistance of the alloy IC-6.     

Effect of alloying elements on the electrochemical polarization behavior and passive film of Fe-Mn base alloys in various aqueous solutions

The corrosion properties of austenitic Fe-Mn, Fe-Mn-Al, Fe-Mn-Cr and Fe-Mn-Al-Cr alloys with compositions of 23-30 wt% Mn, 2.8-8.2 wt% Al and 4.9-6.9 wt% Cr in various aqueous solutions of pH −0.8 to 15.3 and the passivating mechanism induced by the presence of Al, Cr, or Al and Cr have been studied using electrochemical measurements and Auger electron spectroscopic/X-ray photoelectron spectroscopic analysis. Binary Fe-Mn alloys can be passivated only in 10-50% NaOH solutions, and alloying of binary Fe-Mn alloy with Al or Cr or combination of Al and Cr seems not so obviously beneficial to corrosion resistance in HNO₃ or Na₂SO₄ solutions. All of the experimental Fe-Mn based alloys and steels for comparison cannot passivate in either 10% HCl or 3.5% NaCl solution. The Fe-Mn based alloys containing Al or Cr or Al and Cr can passivate in 10-50% HNO₃ or 1 mol l⁻¹ Na₂SO₄ solutions and rainwater. In general, Fe-Mn based alloys can passivate in oxidizing acid, neutral and basic solution, but cannot passivate in reducing acid or solution containing active Cl⁻ ions. In the passive film formed on the surface of Fe-Mn base alloys in various aqueous solutions, bound water and hydroxides are present at the surface of the film, while mixed oxides of Al, Cr, Mn and Fe are located in the inner part. The resistance to corrosion is imparted by a barrier film of bound water, hydroxides and oxides of Al, Cr or Fe, while the Mn oxides in passive film reduce the corrosion resistance.     

Electrochemical behaviour of recasting Ni-Cr and Co-Cr non-precious dental alloys

Corrosion behaviour of dental alloys in artificial saliva was studied using different chemical and electrochemical techniques. The order of corrosion rate for the three alloys in artificial saliva is: wironit < wirolloy < wiron99. This order agrees with the results of chemical studies for determining the cumulative ion concentration using ICP/MS. The open-circuit potential of wirolloy is more positive than wiron99. The higher corrosion rate of wiron99 compared to wirolloy is due to presence of high concentration of Mo. Increasing casting number leads to decrease R_ct value and increasing C_dl.     

补肾活血法治疗慢性再生障碍性贫血疗效的临床评价

目的:评价补肾活血法对慢性再生障碍性贫血(chronic aplastic anemia, CAA) 有效性和安全性。方法:CAA 患者60 例随机分为治疗组和对照组, 治疗组给予补肾活血中药, 对照组给予再障生血片, 采用原位杂交法检测治疗前后骨髓造血细胞IL-2、IL-8水平的变化, 并与正常组18 例相比较。结果:治疗组疗效高于对照组, 基本治愈率分别为66.67 %和40.00 %(P <0.05) 。治疗前CAA 患者骨髓造血细胞IL-2、IL-8 阳性指数均高于正常对照组(P <0.05);各组疗后IL-2、IL-8 阳性指数明显降低(P <0.05);治疗后治疗组IL-2、IL-8 阳性指数高于对照组(P <0.05) 。结论:补肾活血中药能够降低CAA病人骨髓造血细胞IL-2、IL-8 分泌水平, 促进骨髓造血功能恢复。     

阿魏酸乙酯的药理活性及其机制研究

目的: 观察阿魏酸乙酯的药理活性及其机制。方法: 在兔富含血小板血浆(PRP)中加入阿魏酸乙酯和阿魏酸,用ADP诱导血小板的集聚,用TYXN-91 智能血液凝集仪观察血小板聚集率,激光共聚焦显微镜观察血小板细胞聚集时细胞内钙离子的变化情况。制备CCl4 肝损伤小鼠模型,取血清测定谷丙转氨酶(ALT)、谷草转氨酶(AST)活性,取肝组织测定丙二醛(MDA)水平及超氧化物歧化酶(SOD)活性。结果: 不同浓度的阿魏酸乙酯,对ADP诱导的血小板聚集抑制百分数均显著高于等浓度的阿魏酸(n=8,P<0.05)。在阿魏酸乙酯作用下ADP诱导的血小板细胞内钙离子荧光强度的变化(ΔFI)为4.6 ±1.7,明显低于对照组ΔFI 值(10.3 ±2.6,n=8,P<0.01)。阿魏酸乙酯可使肝损伤小鼠组织MDA、血清ALT、AST 含量显著低于对照组,而肝组织的SOD 水平显著高于对照组。结论: 阿魏酸乙酯抑制ADP诱导的血小板聚集作用及对CCl4 引起的小鼠急性肝损伤的保护作用均比阿魏酸强。     

道化法在火灾爆炸危险性评价中的应用

为了确定甲胺生产装置的火灾爆炸危险性,运用美国道(DOW)化学公司火灾爆炸指数评价法最新版本(第七版)对甲胺生产装置进行了定量评价.得出该套生产装置的火灾爆炸危险指数为128,危险程度属于"非常"级别,经过安全措施补偿后,其危险指数降到89.04,危险程度属于"较轻"级别.在安全措施落实的基础上,大大降低了危险性,最后提出用此方法评价时需要注意的几个问题.