复合渗铝钢管焊接HAZ渗铝层相组成特征

采用光镜，电镜，Ｘ射线衍射和电子衍射等测试技术对电感应料浆法（ＧＬ）渗铝钢管焊接接头区域的力学性能和热影响区（ＨＡＺ）渗铝层的相结构特征进行了研究。试验结果表明，ＧＬ渗铝钢管焊接ＨＡＺ渗铝层主要是由α－Ｆｅ（Ａｌ）固溶体，Ｆｅ３Ａｌ相和ＦｅＡｌ构成，渗铝层中不存在含铝较高的ＦｅＡｌ２，Ｆｅ２Ａｌ５和ＦｅＡｌ３等脆性相。显改善了渗铝钢管的承受形变能力和焊接性，使焊接接头区域的组织与性能容易得到保证。     

渗铝钢管的焊接

采用光镜、电镜和Ｘ射线衍射等测试技术对感应料浆法（ＧＬ）渗铝钢管焊接接头区域的力学性能、显微组织、渗铝层厚度、铝浓度及相组成等作了细致的分析。试验结果表明，ＧＬ渗铝钢管渗铝层主要是由α－Ｆｅ（Ａｌ）固溶体、Ｆｅ２Ａｌ和ＦｅＡｌ相构成，不存在含铝较高的脆性相，显著改善了渗铝钢管的焊接性，使焊接接头区域的组织与性能容易得到保证。挂片和生产运行试验也证明了该渗铝钢管焊接区域的抗高温氧化性和耐腐蚀性满足使     

熔盐电解渗铝沉积过程及渗铝层性能研究

研究了熔盐电解渗铝过程中铝的初期沉积现象，长大过程及沉积初期的相结构。结果表明，铝在沉积初期即发生选择性偏聚现象，随着渗铝时间延长，铝继续沉积，并产生聚合扩展，其形态呈球状。在未采取保护措施时，渗铝层表面初期的相组成是Ａｌ２Ｏ３，Ｆｅ２Ｏ３ｔ和Ａｌ５Ｆｅ２。钢铁渗铝后其表面硬度和抗氧化性能明显提高。     

铸铝ZL109激光合金化层的组织和性能研究

采用１０ｋＷ连续横流ＣＯ２激光器在铸造铝硅合金基底上成功地制备了表面合金化（ＬＳＡ）改性层。通过ＳＥＭ、ＴＥＭ分析、显微硬度测试及耐磨性对比试验,研究了ＬＳＡ改性涂层的显微组织结构、相组成和改性效果。结果表明：合金化涂层由γＮｉ（Ｃｒ,Ｆｅ）基体相、Ｎｉ３Ａｌ相、Ｔ（Ａｌ,Ｆｅ,Ｓｉ）相、Ｃｒ／Ｂ相、Ｃｒ２３Ｃ６相等组成,改性层的平均显微硬度为３１０～３６０ＨＶ０．０１,是基底材料的３倍以上。在不同的测试负荷下,ＬＳＡ改性层的耐磨性均比基底材料有很大的提高,相对耐磨性达１０～１２倍。另外,结合表面磨损形貌分析了ＬＳＡ改性层的磨损机理     

渗铝涂层对Ni3Al—Mo基合金高温氧化的防护作用及机理

采用高活度渗铝工艺在ＩＣ－６（Ｎｉ３Ａｌ－Ｍｏ基）合金表面获得内扩散型渗铝涂层，在氩气环境下对渗铝涂层进行扩散处理。利用光学显微镜、ＳＥＭ、ＥＰＭＡ、ＸＲＤ分析研究了涂层的成分及组织结构，测定表明，涂层中的钼以Ｍｏ３Ａｌ沉淀相的形式存在。等温氧化及循环氧化实验表明，渗铝涂层的抗高温氧化性能明显优于ＩＣ－６合金；保护性的Ａｌ２Ｏ３氧化膜阻止了钼的氧化物的形成，避免了ＩＣ－６合金在循环氧化中出现的Ｎｉ     

空心阴极辉光放电膏剂离子渗铝

文中提出了一种新的渗铝方法－辉光加膏剂渗入法，将涂有渗铝膏剂的试样置于阴极空腔中，在辉光放电作用下实现离子渗铝。渗铝膏剂经优选，选出最佳配方：（ｗｔ％）Ａｌ４０％，Ｎａ３ａＦ６５％，ＫＢＦ４５％，ＳｉＣ５０％，用此配方在低碳钢表面１０５０℃＊２ｈ渗铝，其渗铝层厚度可达２３０μｍ。     

渗铝NiAl—20?金属间合金的高温热腐蚀

本文研究了在９５０℃空气中，表面涂Ｎａ２ＳＯ４盐膜的条件下，ＮｉＡｌ，ＮｉａＬ－２０％Ｆｅ及渗铝后的高温热腐蚀行为。在热腐蚀过程中，ＮｉＡｌ合金表面形成ＡｌＯ３膜，显示出一定的耐蚀性能。但Ａｌ２Ｏ３膜易开裂，Ａｌ２Ｏ３膜易开裂，Ａｌ２Ｏ３膜的溶解开裂会引发合工发生快速热腐蚀，２０％Ｆｅ的加入则使ＮｉＡｌ合金的耐蚀性能显著变差，合金表面不能形成单一的Ａｌ２Ｏ３膜；渗铝处理可以明显提高ＮｉＡｌ－２０＾     

渗铝涂层对Ni_3Al－Mo基合金高温氧化的防护作用及机理

采用高活度渗铝工艺在ＩＣ－６（Ｎｉ３Ａｌ－Ｍｏ基）合金表面获得内扩散型渗铝涂层，在氮气环境下对渗铝涂层进行扩散处理．利用光学显微镜、ＳＥＭ、ＥＰＭＡ、ＸＲＤ分析研究了涂层的成分及组织结构，测定表明，涂层中的钼以Ｍｏ３Ａｌ沉淀相的形式存在．等温氧化及循环氧化实验表明，渗铝涂层的抗高温氧化性能明显优于ＩＣ－６合金；保护性的Ａｌ２Ｏ３氧化膜阻止了钼的氧化物的形成，避免了ＩＣ－６合金在循环氧化中出现的ＮｉＭｏＯ４相的多晶型转变，显著改变了合金的抗循环氧化能力；涂层经１０００℃、３００ｈ等温氧化及１０００℃、１００ｈ循环氧化后，未出现β－ＮｉＡｌ相的分解，可认为涂层具有较强的保护作用。     

渗铝钢中性渣系焊条的研制及应用

在研制渗铝钢专用焊条时，打破中性渣系药皮组成的常规，采用了由氧化物、盐等化合物组成的ＣａＯ（ＭｇＯ）－ＳｉＯ２（ＴｉＯ２）－Ａｌ２Ｏ３－ＣａＦ２中性渣系。该焊条各项性能良好，已批量生产。     

高速电弧喷射沉积Fe3Al涂层研究

采用自行研制的电弧喷涂Ｆｅ３Ａｌ合金粉丝材料,成功地用高速电弧喷涂技术制备出Ｆｅ３Ａｌ化合物涂层运用能谱技术（ＥＤＸＡ）、Ｘ射线衍射仪（ＸＲＤ）、扫描电子显微镜（ＳＥＭ）和图像分析仪对涂层成分、显微组织、涂层相结构和组成进行了分析,结果表明,支由以Ｆｅ－２９Ａｌ为主的Ｆｅ３Ａｌ和少量Ｆｅ３Ａｌ基体相和约２０％的α－Ａ１２Ｏ３相组成。对比研究了Ｆｅ３Ａｌ涂层和电站锅炉水冷壁材料２０Ｇ的６５０℃氧化动     

A Controlled New Process of Pack Aluminization

IRON ALUMINIDES exhibit excellent corrosionresistance in aggressive atmospheres at elevatedtemperature'1"41,which enables steels or alloys to beprotected by Fe-Al intermetallic coatings.However,itshould be borne in mind that aluminides with a highaluminum content—FeAl3,Fe2Al5—tend to embrittlethe coated layer and reduce its oxidation resistance.Bycontract,iron-rich iron aluminides possess excellentmechanical properties and oxidation resistance15"61.Aluminum diffusion coatings are oft…     

Cu的添加对X80钢热浸法渗铝层组织的影响

通过在热浸镀铝熔池中添加Cu元素,改善X80钢热浸法渗铝层的组织。在不同的温度下进行扩散退火试验,利用扫描电镜和X射线衍射仪研究退火温度和铜元素对渗层组织的作用机理。采用Smile View软件对渗层厚度进行测量。结果表明,在热浸法渗铝时,Cu的添加可以使合金层/X80钢基体界面间的舌齿状形态缩小,使得界面间反应更均匀。当Cu的添加量为1%(质量分数)时,脆性的Fe₂Al₅合金层的厚度最小。随着扩散退火温度的升高,Cu添加量为1%的试样渗层的界面均匀性增加;扩散退火温度≥600℃时,渗层中开始出现极薄的FeAl相层;扩散退火温度≥650℃时,自由层消失,渗层中出现均匀的FeAl层且渗层外侧出现孔洞;扩散退火温度为700℃时,FeAl层中部出现孔洞带,且渗层外侧出现大孔洞。在热浸镀铝熔池中加入1%Cu元素可以使扩散退火过程中Al原子和Fe原子间的迁移速率差值减小,进而降低Al原子和Fe原子间的浓度梯度。原子间浓度梯度的降低,使得界面间反应更均匀,从而避免渗层中孔洞的出现。     

High temperature corrosion of hot-dip aluminized steel in Ar/1%SO<Subscript>2</Subscript> gas

Carbon steels were hot-dip aluminized in Al or Al-1at%Si baths, and corroded in Ar/1%SO₂ gas at 700-800 °C for up to 50 h. The aluminized layers consisted of not only an outer Al(Fe) topcoat that had interdispersed needle-like Al₃Fe particles but also an inner Al-Fe alloy layer that consisted of an outer Al₃Fe layer and an inner Al₅Fe₂ layer. The Si addition in the bath made the Al(Fe) topcoat thin and nonuniform, smoothened the tongue-like interface between the Al-Fe alloy layer and the substrate, and increased the microhardness of the aluminized layer. The aluminized steels exhibited good corrosion resistance by forming thin α-Al₂O₃ scales, along with a minor amount of iron oxides on the surface. The interdiffusion that occurred during heating made the aluminized layer thick and diffuse, resulting in the formation of Al₅Fe₂, AlFe and AlFe₃ layers. It also smoothened the tongue-like interface, and decreased the microhardness of the aluminized layer. The non-aluminized steel formed thick, nonadherent, nonprotective (Fe₃O₄, FeS)-mixed scales.     

A356浇覆温度对铝/钢复合板界面组织及力学性能的影响

先采用热浸镀铝?锌工艺对Q235钢板进行表面镀层处理,后将液态的A356铝合金定量浇覆于经预热的钢板表面,通过液固铸轧成功制备铝/钢复合板。运用光学显微镜(OM)、SEM观察界面结合与组织形貌,结合EDS、XRD分析界面物相成分,并测试微观硬度、室温拉伸和剪切强度。结果表明:随着浇覆温度的提高,复合板界面间隙消失,整体趋势上扩散层厚度逐渐增加。当浇覆温度为710℃及以上时,界面处会形成Fe3Al、FeAl、FeAl2、Fe2Al5和FeAl3相。在同一浇覆温度下,硬度整体趋势为在Q235和A356基体中保持稳定,而在从Q235侧距界面中心100μm至A356侧距界面中心100μm的范围内连续下降。抗拉强度和剪切强度都表现出先增加后减小的趋势,浇覆温度为710℃时,复合板的成形质量最佳,抗拉强度和剪切强度都为最大,分别为336.4 MPa和137.6 MPa。     

High Temperature Oxidation and Wear Resistance of Y-modified Hot Dipping Aluminized Coating on SCH12 Steel

Microstructures,high-temperature oxidation and wear resistance of hot dipping Al-Si-Y coating on SCH12 heat resistant cast steel were investigated in this study.The aluminized coating was characterized by scanning electron microscopy(SEM),energy dispersive X-ray spectrometry(EDX)and X-ray diffraction(XRD).The results showed that the coating was composed of the Al-rich outer layer and the intermetallics inner layer.In the Al-rich layer,some Y-rich precipitates and Fe-Al-Si-Cr precipitates could be observed.The intermetallics layer presented three layers induced by the increase of Fe,Cr,Ni content and the corresponding decrease of Al,Si content.The oxidation tests were conducted in still air at 850℃for up to 100 h.After oxidation,a top oxide scale composed of mainlyα-Al2O3,Al5Y3O12 was formed on the steel surface.The intermetallics beneath the oxide scale consisted of mainly FeAl and small amount of Fe2Al5 and Cr3Si phase.The mass gain of the coated and uncoated SCH1steel is 0.45 mg/cm 2 and 0.57 mg/cm 2,respectively.The wear resistance was investigated using a high-temperature pin-on-disc tribometer at 650℃.The wear rate for the coated and uncoated steel is 0.45μm 3 /μm.N and 3.01μm 3 /μm.N,respectively.The high temperature wear tests and oxidation tests results demonstrated that the yttrium-modified aluminized specimen had significantly improved high-temperature wear resistance and equivalent oxidation resistance compared with the original SCH12 specimen.     

Features of intermetallic compounds in aluminized steels formed using aluminum foil

Foil aluminizing of steel, wherein Al diffuses to the base steel material by diffusion treatment after hot pressing of the aluminum foil at a lower temperature than the melting point, was performed in this study. Alloy layers formed by diffusion at temperatures ranging from 700 to 1000 °C were investigated, and their features were compared with those of hot-dip aluminized steel. In hot-dip aluminizing, an intermediate Fe₂Al₅ layer was formed between the aluminum layer and the base steel during aluminum coating before the diffusion treatment. In contrast, the coating layer of the foil-aluminized steel specimen after diffusion bonding of the aluminum foil consisted only of the Al layer. An Fe₂Al₅ layer, an FeAl layer and an Al diffused layer were formed in both the aluminized specimens subsequent to the diffusion treatment. The numbers of voids formed in the Fe₂Al₅ layer and at the FeAl/Al diffused layer interface of the foil-aluminized specimens are smaller than those for hot-dip aluminizing. Moreover, the FeAl and Al diffused layers are formed with a greater thickness in the foil-aluminized steel under identical diffusion conditions. The Al concentration in hot-dip aluminized steel decreased in stages from the surface to the base steel, whereas, in the foil-aluminized steel, it decreased gradually. The Fe₂Al₅/base steel interface in the foil-aluminized steel was thus indistinct, and cross-sectional hardness also decreased gradually.     

热浸铝镀层的微观结构及形成机理

在一定温度下，研究了Ｑ２３５钢在不同时间条件下热浸铝时镀层的微观结构变化及形成机理。结果表明，浸铝初期，在铝铁界面产生连续的ＦｅＡｌ３薄层；随时间延长，由于斜方晶格Ｆｅ２Ａｌ５相的快速生长，抑制了ＦｅＡｌ３相的进一步形成，使ＦｅＡｌ３相由初期的连续层向非连续相层转变，而Ｆｅ２Ａｌ５相呈不均匀齿状垂直于基体表面生长。通过ＳＥＭ及ＴＥＭ分析了镀层形成机理并提出了镀层的结构模型。     

热浸铝钢等离子体电解氧化陶瓷层的微观力学特性

采用纳米压入方法表征了热浸镀铝钢表面由Al2O3层、Al层和FeAl层组成的复合涂层的纳米硬度、弹性模量及断裂韧性等微观力学性能,采用扫描电镜(SEM)观察了纳米压痕形貌,并分析了孔洞对陶瓷层的纳米压入行为和压痕裂纹扩展的影响.结果表明:等离子体电解氧化(PEO)陶瓷层中包含许多微米和亚微米尺度的细小孔洞,陶瓷层弹性模量约为226.4 Gpa,纳米硬度约为19.6 Gpa.当纳米压入深度为250 nm时,所测得陶瓷层的力学参数分散性较大.与FeAl层比较,PEO陶瓷层具有较高的裂纹扩展阻力. FeAl层纳米压痕顶端产生了沿直线扩展的径向裂纹;而陶瓷层纳米压痕中除径向裂纹外出现了侧边裂纹.     

稀土Ce对热浸渗铝扩散层生长和组织的影响

研究了稀土Ce对15CrMo钢热浸渗铝扩散层生长的影响;采用OM、SEM和EDS分析了扩散层的组织、成分和相结构。结果表明,扩散层由η相(Fe2Al5)、ξ相(FeAl2)、β2相(FeAl)、β1相(Fe3Al)和α相组成,其中η相和ξ相是主要相;添加稀土Ce将减少扩散层中的孔洞,细化晶粒,并明显减少η相;稀土Ce对扩散层的生长起一定的阻碍作用,这种作用的大小与Ce的添加量密切有关。     

H13热作模具钢微弧氧化复合陶瓷层的组织和性能

通过热浸镀铝/微弧氧化复合工艺对H13模具钢进行表面改性以提高模具表面质量。在热浸镀铝过程中,将H13钢基体浸入710℃纯铝液6 min,得到了以Fe2Al5为主中间合金层,使得镀层与基体紧密结合。经过微弧氧化处理后,镀铝试样表面铝层转化为氧化铝陶瓷,主要由α-Al2O3和γ-Al2O3相组成。用带有能谱分析装置(EDX)的扫描电镜(SEM)、X射线衍射(XRD)分析了膜层的形貌、成分和相组成。微弧氧化陶瓷层主要由Al、O、Si元素组成,其中O、Si主要来源于硅酸盐电解液。