Molecular dynamics of structural properties of molten CaO-SiO2 with varying composition

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｓｔｕｄｙｏｆｍｏｌｔｅｎｓｔｒｕｃｔｕｒｅｏｆＣａＯ ＳｉＯ2 ,ｗｈｉｃｈａｃｔａｓｔｈｅｂａｓｉｃｆａｃｔｏｒｉｎｆｌｕｅｎｃｉｎｇｔｈｅｐｈｙｓｉｃａｌａｎｄｃｈｅｍｉｃａｌｐｒｏｐｅｒｔｉｅｓｏｆｔｈｅｓｉｌｉｃａｔ     

Kinetics of electrochemical corrosion of chalcopyrite in presence of bacteria

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｉｍｐｏｒｔａｎｔｂａｃｔｅｒｉａｉｎｂｉｏｈｙｄｒｏｍｅｔａｌｌｕｒｇｙａｒｅｍａｉｎｌｙａｅｒｏｂｉｃｃｈｅｍｏｌｉｔｈｏｔｒｏｐｈｉｃｓｐｅｃｉｅｓ ,ｏｆｗｈｉｃｈｔｈｅｍｏｒｅｉｍｐｏｒｔａｎｔａｒｅＴｈｉｏｂａｃｉｌｌｕｓｆｅｒｒｏｏｘｉ ｄａｎｓａｎｄＴｈｉｏｂａｃｉｌｌｕｓｔｈｉｏｏｘｉｄａｎｓ .ＴｈｅｐｒｏｐｅｒｔｉｅｓｏｆｔｈｅｔｗｏｓｐｅｃｉｅｓａｒｅｓｈｏｗｎｉｎＴａｂｌｅ 1.Ｔｈｅｙｃａｔａｌｙｚｅｔｈｅｏｘｉｄａｔｉｏｎｏｆｓｏｍｅｏｒａ…     

Semi-conductive properties of melanization of chromate zinc plates

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｃｏｒｒｏｓｉｏｎｏｆａｃｈｒｏｍａｔｅｚｉｎｃａｔｔｈｅｉｎｉｔｉａｌｓｔａｇｅｉｓｔｈｅｄｅｃｒｅａｓｉｎｇ ｐｒｏｃｅｓｓｏｆｓｕｒｆａｃｅｌｉｇｈｔｎｅｓｓ ,ａｎｄｉｓｕｓｕａｌｌｙｃａｌｌｅｄｍｅｌａｎｉｚａｔｉｏｎ (ｂｌａｃｋ ｐａｔｉｎａ)ｏｆｚｉｎｃｐｌａｔｅｏｆｗｈｉｃｈｔｈｅｐｒｏｄｕｃｔｉｓＺｎ1 δＯｗｉｔｈｔｈｅｐｒｏｐｅｒｔｙｏｆａｎｎ ｔｙｐｅｓｅｍｉ ｃｏｎｄｕｃｔｏｒ ,ａｎｄｔｈｅｉｌｌｕｍｉ ｎａｔｉｏｎｓｕｐｐｒｅｓｓｅｓｔｈｅｍｅ…     

Behavior of Fe and S in bioleaching of pentlandite

1　ＩＮＴＲＯＤＵＣＴＩＯＮＯｘｉｄｉｚｉｎｇｐｒｏｃｅｓｓｂｙａｕｔｏｔｒｏｐｈｉｃｂａｃｔｅｒｉａ ,ｓｕｃｈａｓＴｈｉｏｂａｃｉｌｌｕｓｆｅｒｒｏｏｘｉｄａｎｓ (Ｈｅｒｅｉｎｂｅｌｏｗｂｅａｂｂｒｅ ｖｉａｔｅｄｔｏＴ .ｆ .) ,ｈａｓｂｅｅｎｗｉｄｅｌｙ     

Genetic optimization of reliability design of machine element

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｒｅｌｉａｂｉｌｉｔｙｄｅｓｉｇｎｏｐｔｉｍｉｚａｔｉｏｎｏｆｍａｃｈｉｎｅｃｏｍｐｏｎｅｎｔｉｓｂａｓｅｄｏｎｔｈｅｆｏｕｎｄａｔｉｏｎｏｆｎｅｏｔｅｒｉｃｍａｔｈｅｍａｔｉｃａｌｐｒｏｂａｂｉｌｉｔｙ ,ｍａｔｈｅｍａｔｉｃａｌｓｔａｔｉｓｔｉｃｓａｎｄｏｐｔｉｍｉｚａｔｉｏｎ .Ｉｔｕｓｕａｌｌｙｄｅａｌｓｗｉｔｈｈｉｇｈｄｉｍｅｎｓｉｏｎａｌ,ｎｏｎｃｏｎｖｅｘａｎｄｎｏｎｌｉｎｅａｒｏｂｊｅｃｔｆｕｎｃｔｉｏｎｓｓｕｂｊｅｃｔｔｏｖａｒｉｏｕｓｓｔｏｃｈａｓ…     

Influence of phase components of tungsten oxide on homogeneity of ultrafine tungsten powder

1　ＩＮＴＲＯＤＵＣＴＩＯＮＨｙｄｒｏｇｅｎｒｅｄｕｃｔｉｏｎｏｆｔｕｎｇｓｔｅｎｏｘｉｄｅｓ,ｓｕｂｓｅｑｕｅｎｔｍｉｘｉｎｇｗｉｔｈｃａｒｂｏｎｂｌａｃｋａｎｄｃａｒｂｕｒａｔｉｎｇｉｓｔｈｅｍｏｓｔｃｏｍｍｏｎｗａｙｔｏｐｒｏｄｕｃｅｔｕｎｇｓｔｅｎｃａｒｂｉｄｅｐｏｗｄｅｒｓｆｏｒｔｈｅｈａｒｄｍｅｔａｌｉｎｄｕｓｔｒｙ.Ｔｈｉｓｔｅｃｈｎｉｑｕｅｈａｓｂｅｅｎｐｒａｃｔｉｃｅｄｆｏｒｄｅｃａｄｅｓａｎｄｃａｌｌｅｄ“ｃｏｎｖｅｎｔｉｏｎａｌｈｙｄｒｏｇｅｎｒｅｄｕｃｔｉｏｎｐｒｏｃｅｓｓ…     

Microstructure and properties of composite of stainless steel and partially stabilized zirconia

1　ＩＮＴＲＯＤＵＣＴＩＯＮＯｗｉｎｇｔｏｔｈｅｒｅｑｕｉｒｅｍｅｎｔｓｏｆｒｅｐｅａｔｅｄｓｅｒｖｉｃｅａｎｄｌｏｎｇｗｏｒｋｉｎｇｔｉｍｅｏｆｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｂｕｒｎｅｒｓ ,ｓｕｃｈａｓｓｐａｃｅｃｒａｆｔｅｎｇｉｎｅ ,ｔｈｅｍａｔｅｒｉａｌｏｆｔｈｅｂｕｒｎｅｒｓｓｈｏｕｌｄｈａｖｅｇｏｏｄｓｔｒｕｃｔｕｒｅｐｒｏｃｅｓｓａｂｉｌｉｔｙ ,ａｓｗｅｌｌａｓｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｒｅｓｉｓｔａｎｃｅ ,ｔｈｅｒｍａｌｓｈｏｃｋｒｅｓｉｓｔａｎｃｅａｎｄｔｈｅｒｍａｌｆａｔｉ…     

Formation of surface coating on milling balls during milling of Cr powders

1　ＩＮＴＲＯＤＵＣＴＩＯＮＮｅｗｍａｔｅｒｉａｌｓ ,ｓｕｃｈａｓｄｉｓｐｅｒｓｉｏｎｓｔｒｅｎｇｔｈｅｎｅｄａｌｌｏｙ ,ａｍｏｒｐｈｏｕｓａｎｄｉｎｔｅｒｍｅｔａｌｌｉｃｓ ,ｃａｎｂｅｏｂｔａｉｎｅｄｂｙｍｅｃｈａｎｉｃａｌａｌｌｏｙｉｎｇｗｈｉｃｈｓｈ     

Control of deflection deformation of plate-shape castings in solidification

1　ＩＮＴＲＯＤＵＣＴＩＯＮＡｎｏｒｄｅｒｏｆｌａｒｇｅｐｌａｔｅｃａｓｔｉｎｇｓｕｓｕａｌｌｙｂａｆｆｌｅｓｔｈｅｍａｎｕｆａｃｔｕｒｅｓ,ａｓｔｈｅｄｅｆｌｅｃｔｉｏｎｄｅｆｏｒｍａｔｉｏｎｉｓｌｉａｂｌｅｔｏｏｃｃｕｒｄｕｒｉｎｇｓｏｌｉｄｉｆｉｃａｔｉｏｎｏｆｔｈｅｃａｓｔｉｎｇｓ .Ｔｈｅｃｏｍｍｏｎｗａｙｔｏｓｏｌｖｅｔｈｉｓｐｒｏｂｌｅｍｉｓｔｏｐｕｒｓｕｅａｎｏｐｔｉｍｕｍｃａｓｔｉｎｇｐｒｏｃｅｓｓｒｏｕｔｅｂｙｔｒｉａｌａｎｄｅｒｒｏｒｍｅｔｈｏｄ ,ｏｒｔｏｋｅｅｐｌａｒｇｅｒｍ…     

Electrochemical behavior of chalcopyrite in presence of Thiobacillus ferrooxidans

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｏｂｌｉｇａｔｅｃｈｅｍｏａｕｔｏｔｒｏｐｈｉｃｂａｃｔｅｒｉａｗｈｉｃｈｉｓｎａｍｅｄＴｈｉｏｂａｃｉｌｌｕｓｆｅｒｒｏｏｘｉｄａｎｓ,ｉｓｔｈｅｐｒｉｍａｒｙｏｒ ｇａｎｉｓｍｉｍｐｌｉｃａｔｅｄｉｎｔｈｅｂｉｏｌｅａｃｈｉｎｇｏｆｓｅｖｅｒａｌｓｕｌ ｆｉｄｅｓ .Ｉｔｓｃｏｍｍｅｒｃｉａｌｐｏｔｅｎｔｉａｌｉｎｔｈｅｒｅｃｏｖｅｒｙｏｆｍｅｔ ａｌｆｒｏｍｌｏｗ ｇｒａｄｅａｎｄｒｅｆｒａｃｔｏｒｙｏｒｅｓ ,ｄｅｓｕｌｆｕｒｉｚａｔｉｏｎｏｆｃｏａｌｓ ,ａｎｄｉ…     

Repair of NiCrAlYSi overlay coating on Ni3Al base alloy IC6

The effect of repair of NiCrAlYSi coating after long time use on the coherence of coating to substrate and mechanical properties of Ni₃Al base alloy IC6 has been studied. The alloy with NiCrAlYSi coating was stressed under the condition of 900 °C/100 MPa for 200 h to simulate the service condition of IC6 turbine vanes. The results showed that the coherence of base alloy/original coating, original coating/first repair coating, first repair coating/second repair coating or base alloy/second repair coating was firm. The interfaces between them had no cracks and porosity, for either partly or entirely repaired coatings. However, there were more Mo rich particles in the affected zone compared with original coating. Compared with IC6 alloy aged at 900 °C for 200 h, the yield strength at ambient temperature of IC6 alloy with first repair coating was almost equivalent, while the elongation decreased slightly; its stress rupture life under 1100 °C/90 MPa condition was about 100 h. For secondary coating repair, the room temperature tensile properties of base alloy had no obvious change, while stress rupture lives decreased, but still were rather long, compared to the alloy with first repair coating. Therefore, NiCrAlYSi coating repair is feasible to prolong the service lives of IC6 turbine vanes.     

DIFFUSION PHENOMENA AND MICROSTRUCTURE STABILITY OF Ni－Cr－Al－Y－Si COATING ON THENi_3Al BASED ALLOY SUBSTRATE

ＤＩＦＦＵＳＩＯＮＰＨＥＮＯＭＥＮＡＡＮＤＭＩＣＲＯＳＴＲＵＣＴＵＲＥＳＴＡＢＩＬＩＴＹＯＦＮｉ－Ｃｒ－Ａｌ－Ｙ－ＳｉＣＯＡＴＩＮＧＯＮＴＨＥＮｉ_３ＡｌＢＡＳＥＤＡＬＬＯＹＳＵＢＳＴＲＡＴＥＺ．Ｐ．Ｘｉｎｇ;Ｙ．Ｆ．Ｈａｎ;Ｙ．Ｌ．ＪｉａｎｄＭ．Ｇ?..     

The corrosion behavior of TiN coated and uncoated incoloy 800 alloy

Incoloy alloy 800 is used in a variety of applications in industry as well as in domestic appliances for sheeting on electric heating elements. The composition of the alloy enables it to resist deterioration in many corrosive environments. However, resistance of the alloy to corrosion in aqueous media needs to be further examined. The present study examines the corrosion properties of Incoloy 800 alloy of both coated and uncoated workpieces obtained in a 0.1N H₂SO₄ + 0.05N NaCl solution. TiN coating is achieved using a physical vapor deposition (PVD) technique while corrosion tests are carried out using electrochemical polarization methods. Moreover, in order to examine the influence of hydrogen diffusion, reduction of hydrogen at the Incoloy 800 surface is carried out in a solution of 0.1N HNO₃ + 1 g/L thiourea. Tensile tests are conducted on the workpieces to determine the influence of hydrogen embrittlement on the resulting mechanical properties of the substrate. To examine the pit formation and stress induced microcracking, scanning electron microscope (SEM) analysis is carried out. The results show that the corrosion resistance of the alloy improves after TiN coating. In addition, no specific pattern or differentiation on the pit geometry is observed. The pitting rate and its size reduce considerably for TiN coated workpieces.     

Mechanical Performance of Cold-Sprayed A357 Aluminum Alloy Coatings for Repair and Additive Manufacturing

Cold-sprayed coatings made of A357 aluminum alloy, a casting alloy widely used in aerospace, underwent set of standard tests as well as newly developed fatigue test to gain an information about potential of cold spray for repair and additive manufacturing of loaded parts. With optimal spray parameters, coating deposition on substrate with smooth surface resulted in relatively good bonding, which can be further improved by application of grit blasting on substrate’s surface. However, no enhancement of adhesion was obtained for shot-peened surface. Process temperature, which was set either to 450 or 550 °C, was shown to have an effect on adhesion and cohesion strength, but it does not influence residual stress in the coating. To assess cold spray perspectives for additive manufacturing, flat tensile specimens were machined from coating and tested in as-sprayed and heat-treated (solution treatment and aging) condition. Tensile properties of the coating after the treatment correspond to properties of the cast A357-T61 aluminum alloy. Finally, fatigue specimen was proposed to test overall performance of the coating and coating’s fatigue limit is compared to the results obtained on cast A357-T61 aluminum alloy.     

Mechanical Properties of TiN Coating on Nanocrystalline Surface Layer of 304 Stainless Steel

Surface nanocrystallization(SNC)can markedly improve surface mechanical properties of metallic materials and accelerate thermal diffusion of elemental atoms.In this work we study the effects of SNC on structure and mechanical properties of TiN coating on 304 stainless steel substrate.The steel was subjected to 15 min surface mechanical attrition treatment(SMAT)to obtain a nanocrystalline surface layer with thickness about 30μm.TiN coating was deposited on the surface nanocrystallized and the coarse-grained steel substrates by multi-arc ion plating.X-ray diffraction shows that TiN(111)orientation of the coating is much reduced due to SNC treatment.Mechanical tests show that the nanocrystalline surface layer has obviously increased surface hardness of the coating system;toughness and adhesion of the coating,impact resistance of the coating system are also improved.Advantages of SNC-hard coating processing over the conventional duplex treatment consisting of thermal diffusion process-hard coating are shortly discussed.     

表层绝热对定向凝固Ni60合金涂层凝固行为的影响

采用超音速等离子喷涂技术在45钢基体上制备Ni60合金涂层,在高频感应重熔+强制冷却处理条件下,研究了表面散热条件对涂层的组织结构、元素分布和性能的影响。结果表明:在自然散热条件,涂层形成了定向树枝晶结构组织,通过表面覆盖层的保护,改变表面散热条件,使涂层组织向具有熔结特征的等轴晶转变,并且形成了两个明显不同组织的区域,在靠近基体区域,组织细小致密,但组织和元素分布不均匀;而靠近涂层表面区域,组织具有长大现象,但元素和组织均匀性明显提高。相对于未加覆盖层涂层,附加覆盖层的涂层元素和基体元素在界面处具有更充分的扩散,基体元素向涂层中的扩散较涂层元素向基体扩散更加强烈。覆盖层的附加明显提高了涂层硬度,使涂层表面的宏观硬度由33.4 HRC提高到54.4 HRC,涂层截面的显微硬度由566.1 HV0.2提高到659.2 HV0.2。     

Oxidation,Mechanical and Tribological Behaviors of the Ni/cBN Abrasive Coating-Coated Titanium Alloys

In order to improve the oxidation and wear resistance of blades tip of titanium alloys as well as the sealing performance of the gas turbine engine,a Ni/cBN abrasive coating was prepared on titanium alloys through composite electroplating.Oxidation,mechanical and tribological properties of the abrasive coating were investigated.Furthermore,the effect of the oxidation on the mechanical and tribological properties was also evaluated.Oxidation results revealed that the abrasive coating underwent slight oxidation within 700 ℃.Meanwhile,some intermetallic compounds,Ni_3Ti,NiTi and NiTi_2,were formed at the coating/substrate interface during oxidation.Due to the pinning effect of cBN particles and the different thermal expansion coefficients of the coating and substrate,the coating/substrate interface was cracked after oxidation at 700℃.Tensile results showed that the presence of coating reduced the strength of the alloy significantly at room temperature,while only marginal variations of the strength of the coated and uncoated specimens at elevated temperatures.Besides,the wear tests indicated that the coating had the excellent cutting ability and wear resistance,which can effectively protect the blades tip of titanium alloys.As the temperature increased,the wear resistance decreased due to the decrease in the mechanical properties of the Ni/cBN coating.     

羟基磷灰石涂层及其热处理对TLM合金基体的影响

利用DTA/TG、XRD方法研究溶胶凝胶法制备羟基磷灰石(HA)烧结热处理过程中的相转变规律,同时研究制备HA涂层时保温处理对TLM(TiZrSnMoNb系)合金基体力学性能的影响.结果表明,在制备HA涂层的过程中.热处理温度为450～1000℃,所得的HA的晶化程度较高,较纯净.     

Ti-6Al-4V合金表面渗层制备及空蚀性能研究

目的利用化学热处理对钛合金表面进行扩渗处理,制备硬质表面渗层,以提高钛合金抗空蚀能力。方法采用氮气气氛下渗铝工艺对Ti-6Al-4V合金退火试样进行表面处理,获得硬质表面渗层。利用X射线衍射仪、扫描电子显微镜、能谱分析仪和显微硬度计表征分析表面渗层的物相组成、微观结构、元素分布及力学性能。利用超声波振动空蚀试验机,按照ASTM G32标准,测试表面渗层在去离子水中的空蚀性能,并结合空蚀后表面形貌和元素分布,研究分析其空蚀机理。结果扩渗处理在Ti-6Al-4V合金表面生成了具有较高显微硬度的表面渗层,其由最外面的化合物层和内部的扩散层构成。在1023 K温度下处理1 h的试样,其表面渗层均匀、致密、无微裂纹,在去离子水中空蚀12 h的累积质量损失最小,为未处理试样的18%,抗空蚀性能最好。随着处理时间的延长和处理温度的升高,渗层表面变得不平整,且表面凸出的硬质陶瓷颗粒物增多。硬质陶瓷颗粒物虽显著增加试样的显微硬度,但易诱发空泡生成,使抗空蚀性能变差。结论氮气下渗铝处理在Ti-6Al-4V合金表面获得的表面渗层可以改善合金的抗空蚀性能,而表面凸出的大小不均的硬质陶瓷颗粒物使表面渗层的抗空蚀性能减弱。     

热喷涂及热处理对45钢表面组织和性能的影响

采用金相显微镜、扫描电镜分析和显微硬度测试等手段,研究了喷焊及回火温度对镍基自熔合金粉末涂层组织和性能的影响。结果表明:在结合面上,元素互相扩散,形成亮白色带状的过渡层,基体母材区受热较少,组织变化不大。碳元素扩散进入喷焊层后,与Cr形成(Fe,Ni)23C6及Cr的碳化物,这些硬质相阻碍喷焊层晶粒的张大,致使晶粒细化,在45钢中形成粗棒状或块状组织。喷焊层与基体之间形成了良好的冶金结合,合金元素在喷焊层与基体界面附近连续分布,保证了较高的结合强度。