基于系列磨片的纯铁渗硼层形貌三维重建

为了解渗硼层硼化物的生长过程,采用系列磨片和计算机三维重建技术与可视化,研究了纯铁渗硼层硼化物的立体形貌.结果表明:渗硼层的硼化物以柱状晶形式向基体生长,同时柱状晶也在横向生长,纵向生长速度大于横向生长速度;处于表面的柱状晶根部连在一起形成连续的渗硼层,柱状晶生长过程中会出现倾斜和合并;三维形貌的二维剖面形貌呈齿状,与实际二维金相组织一致;从不同剖面方向观察同一硼化物,硼化物形态不尽相同,二维图像不能完全反映硼化物的真实形貌.     

低碳钢液相等离子体电解硼碳共渗层生长特性研究

在含有硼砂和甘油的电解液中对Q235低碳钢表面进行液相等离子体电解硼碳二元共渗(PEB/C)处理,研究不同时间条件下PEB/C共渗层的组织形貌,着重探讨了PEB/C二元共渗过程中电解质的分解反应和渗硼层快速生长机理。结果表明,在330V电压条件下,经过6min PEB/C处理后,在样品表面开始生成不连续的岛状硼化物;而经过30min PEB/C处理后,可以形成主要由Fe2B相组成的均匀致密的渗硼层,渗硼层的硬度可以达到1 800HV,厚度约为20μm。PEB/C共渗样品渗硼层的生长过程主要包括共渗初期阶段、生成岛状硼化物阶段和渗硼层均匀生长阶段。     

粉未渗硼中脆性影响因素研究

本文采用作者研制的三点弯曲小冲程脆性试验架对渗硼层脆性影响因素进行了研究,这些因素是渗硼剂中供硼剂和活性剂数量,渗硼温度,时间等,对试样表面光洁度及渗硼后冷却方式对渗硼层脆性的影响也做了研究。     

微波渗硼层中FeB的形成机理研究

通过微波处理、X射线衍射和扫描电镜等手段研究了微波场下渗硼层中FeB的形成机理,并与常规渗硼层进行了比较.结果表明,FeB向渗层内部采取(002)晶向取向生长,渗层表面无取向特征,且微波渗硼FeB相的生长不受表面硼化物晶核密度控制.     

钛合金表面阳极微弧等离子体渗硼层的研究

采用阳极微弧等离子体技术研究了钛合金表面渗硼层的微观组织和性能。通过光学显微镜、扫描电镜(SEM)、X射线衍射仪(XRD)、能谱仪(EDS)表征分析了渗硼层的表面和截面的微观组织、形貌、相结构、渗层元素分布。借助摩擦磨损试验机测试了渗硼层的耐磨性,运用电化学工作站对渗硼后的TC4材料进行了耐腐蚀性测试。结果表明,钛合金表面阳极微弧等离子体渗硼技术制备的渗硼层连续致密。渗硼层主要由金属间化合物TiB2和TiB组成,其与氧化层共同作用,能显著提高钛合金表面的耐磨性。渗硼后的TC4钛合金耐腐蚀性较基体有所降低。表面阳极微弧等离子体技术是一种新型的钛合金表面改性方法。     

奥氏体不锈钢渗硼层的形成及其生长动力学过程

用光学显微镜，透射电镜，电子衍射，Ｘ射线衍射研究了奥氏体不锈钢渗硼层的形成及其动力学过程，结果表明，渗层形成过程，先形成含Ｂ固溶体，超过固溶度形成ＦｅＢ，最后形成ＦｅＢ并有Ｆｅ３（ＣＢ）同时存在，渗硼层生长厚度随时间变化关系符合抛物线规律。硼化物形核初期呈粒状，后沿（００２）晶向优先长大呈棒状，对硼化形成（００２）择优取向的原因和不能形成指状生长形貌硼化物层的原因进行了探讨。     

渗硼层表面脆性测量方法探讨

研究了显微硬度压痕法结合声发射技术在渗硼层表面进行脆性检测的可行性。结果表明，渗硼层表面测量的声发射能量累积计数值Ｅｎ与显微硬度压痕负荷Ｐ之间基本保持线性关系，可以用Ｅｎ－Ｐ直线方程的斜率Ｋ值定量表征渗硼层的脆性。渗硼层表面疏松较重，则给这种脆性检测方法带来一定影响。     

TA2熔盐电解法渗硼的研究现状及展望

钛及其合金作为21世纪重要的结构材料,具有抗腐蚀、熔点高、密度小、比强度高、无磁性及生物相容性等优点,但表面硬度低、耐磨性差、摩擦系数大,严重限制了其应用范围.熔盐电解法渗硼作为一种金属表面改性技术,具有成本低廉、效果明显等优点,可有效提高钛及其合金的表面硬度和耐磨性.综述了熔盐电解法渗硼的研究现状,从渗硼的工艺参数、机理、热力学和动力学方面进行了分析.综合双相硼化物(TiB和TiB2)渗层的生长动力学的研究结论,可以看出渗硼问题的核心就是活性B原子在固相的扩散,因此研究近相变温度下B原子的扩散行为对渗硼过程尤为重要.     

稀土元素的摩擦催渗作用及宏观催渗机制

将稀土化合物和硼化物加入润滑油中进行摩擦磨损试验,用Ａｕｇｅｒ电子能谱研究摩擦亚表面稀土元素和硼的分布,结果表明,Ｌａ,Ｐｒ,Ｓｍ和Ｇｄ对硼均具有摩擦催渗作用。Ｘ射线光电子能谱的分析表明,稀土元素对硼化物的分解具有“摩擦催化裂化”作用,使摩擦表面活性硼原子增加,从而使硼渗层增加,提高了材料的耐磨性。     

渗硼层与渗氮层深度的测定

以H13钢的渗氮层和渗硼层为例，借助于光学显微镜、扫描电镜(SEM)、显微硬度计和X射线衍射(XRD)，分析了两者组织形态和硬度梯度上的差别，指出了两者渗层深度不同的界定标准。即渗硼层厚度的测量不能将过渡层记入渗硼层厚度，而应采用硼化物齿峰和齿谷的统计算术平均值得到渗硼层厚度。     

Superplastic boronizing of duplex stainless steel under dual compression method

In this work, SPB of duplex stainless steel (DSS) under compression method is studied with the objective to produce ultra hard and thick boronized layer using minimal amount of boron powder and at a much faster boronizing time as compared to the conventional process. SPB is conducted under dual compression methods. In the first method DSS is boronized using a minimal amount of boron powder under a fix pre-strained compression condition throughout the process. The compression strain is controlled in such a way that plastic deformation is restricted at the surface asperities of the substrate in contact with the boron powder. In the second method, the boronized specimen taken from the first mode is compressed superplastically up to a certain compressive strain under a certain strain rate condition. The process in the second method is conducted without the present of boron powder. As compared with the conventional boronizing process, through this SPB under dual compression methods, a much harder and thicker boronized layer thickness is able to be produced using a minimal amount of boron powder.     

渗硼层形成机理的探讨

渗硼层的形成机理,一直是渗硼研究的重要课题。本文主要采用X射线法对用气体法在工业纯铁上形成渗硼层的过程进行了研究。结果表明,在渗硼时,依次形成硼的固济体,Fe_2B、FeB。即渗硼层形成过程完全符合相图和相律。     

Q235钢固体粉末渗硼及渗层生长动力学行为

各类材料渗硼工艺不同,硼的扩散也不同,其中有许多现象往往不能定量分析.采用固体粉末法对Q235钢进行了渗硼,得到的渗硼层为锯齿状,垂直于钢表面楔入基体.用sigma Plot 10.0软件对试验数据进行了分析和拟合,得出了渗硼层等厚度图,为制定渗硼工艺提供了依据:利用此图,既可以对设定的渗硼时间和温度预测渗硼层厚度,又可以用一定的固体渗硼厚度值确定渗硼时间和温度.通过动力学研究得到了渗层相组成为单一的Fe2B相硼,在不同温度下的扩散速率常数:K800℃=1.074×10-13m2/s,K850℃=1.622×10-13m2/s,K900℃=3.921×10-13m2/s,平均扩散激活能为134.473 kJ/mol.     

Optimization of process parameters of boro-carburized low carbon steel for tensile strength by Taquchi method with grey relational analysis

The results of study on the boro-carburizing and boronizing of AISI 1015 steel on tensile strength was carried out by Taquchi-grey relational method. The orthogonal array L₉(3⁴) was used to conduct the experiment. The thickness of boride layer increased with increase in process temperature and time. The thickness of boride layers for boronized AISI 1015 steel was more than the pre-carburized and boronized AISI 1015 steel. The microhardness decreased with increase in distance from the surface to the core. However, the hardness gradient reduced gradually from the surface to the core in case of boro-carburized treatments compared to boronized treatments. The optimal process parameters and their levels for pre-carburized AISI 1015 steel are carbon content 0.45% at 950 °C temperature and 4 h process duration. The results revealed that process time, case carbon content and process temperature influenced the yield strength and % elongation. The ultimate strength is influenced by the process temperature, process time and carbon content. The process temperature was the most influential control factor that affects the tensile strength properties.     

Investigation of electrochemical corrosion behavior in a 3.5 wt.% NaCl solution of boronized dual-phase steel

In this study, corrosion behaviors of boronized and non-boronized dual-phase steel were investigated with Tafel extrapolation and linear polarization methods in a 3.5 wt.% NaCl solution. Microstructure analyses show that the boride layer on the dual-phase steel surface had a flat and saw smooth morphology. It was detected by X-ray diffraction (XRD) analysis that the boride layer contained FeB and Fe₂B phases. The amount of martensite increases with an increase in the intercritical annealing temperature. Both the amount of martensite and the morphology of the phase constituents have an influence on the corrosion behavior of dual-phase steel. A higher corrosion tendency was observed with an increased amount of martensite. The corrosion resistance of boronized dual-phase steel is higher compared with that of dual-phase steel.     

Effects of boronizing on mechanical and dry-sliding wear properties of CoCrMo alloy

In this study, CoCrMo alloy was boronized at 950 °C for 2, 4, 6 and 8 h, respectively. The boronized samples were characterized by scanning electron microscopy, X-ray diffraction, microhardness tester and ring-on-block wear tester. X-ray diffraction studies showed the boride layer formed at 950 °C for 2–8 h consisted of the phases Co₂B and CrB. A large number of pores formed in diffusion zone were probably attributed to the Kirkendall effect. Depending on boronizing time, the thickness of boride layer ranged from 4 to 11 μm. The excellent wear resistance of the boronized CoCrMo alloy was attributed to the high surface hardness of the Co₂B and CrB under dry-sliding conditions when compared to the as-received state.     

Plasma paste boronizing of AISI 8620, 52100 and 440C steels

In the present study, AISI 8620, 52100 and 440C steels were plasma paste boronized (PPB) by using 100% borax paste. PPB process was carried out in a dc plasma system at temperature of 700 and 800 °C for 3 and 5 h in a gas mixture of 70%H₂–30%Ar under a constant pressure of 4 mbar. The properties of boride layer were evaluated by optical microscopy, X-ray diffraction and Vickers micro-hardness tester. X-ray diffraction analysis of boride layers on the surface of the steels revealed FeB and Fe₂B phases for 52100 and 8620 steels and FeB, Fe₂B, CrB and Cr₂B borides for 440C steel. PPB process showed that since the plasma activated the chemical reaction more, a thicker boride layer was formed than conventional boronizing methods at similar temperatures. It was possible to establish boride layer with the same thickness at lower temperatures in plasma environment by using borax paste.     

L415/IN825复合板焊接接头渗硼处理工艺及渗层的组织与性能

目前对双金属复合板焊接接头的渗硼处理鲜有研究报道。为了提高双金属复合板焊接接头的耐蚀和耐磨性能,对其表面进行渗硼处理。采用光学显微镜(OM)、扫描电镜(SEM)、X射线衍射仪(XRD)及显微硬度计分别对L415/IN825复合板复层焊接接头渗层的微观组织、物相组成及显微硬度进行了分析,并研究了复合板焊接接头及其渗层电化学腐蚀性能。结果表明:复合板焊接接头复层渗层分为硼化物层(Ni_2B、Cr_5B_3、Cr_2B和CrB)和硅化物层(Ni_2Si、Cr_3Ni_2Si和Cr_(13)Ni_5Si_2),全渗层的厚度随着加热温度和保温时间的增加而增加;不同区域渗层表面的显微硬度值均高于基体;复合板焊接接头基体耐蚀性能优于焊接接头表面渗层。     

Investigation of the effect of boronizing on cast irons

Gray iron, ductile iron and compacted graphite iron were boronized with solid boron-yielding substances by box-boronizing method. Commercial EKabor^® 3 powder is used as the boronizing agent and the treatments are carried out at 850, 900 and 950°C for 2, 3, 4, 5 and 6 h. Thickness and microhardness of the boride layer, and the microstructure of the boronized specimens are reported.     

The Effect of Precarburizing Treatment on Morphology of the Boride Layer

Structural steel samples were boronized with a newly introduced boronizing pack containing boric acid (H₃BO₄), cryolite (Na₃B₄O₇), aluminum and aluminum oxide (Al₂O₃). In this research, the effect of precarburizing treatment on the morphology of the boride layer was studied and compared with unprecarburized specimens. The treated specimens were characterized using SEM, x-ray diffractometry, ED AX and microhardness tester. The results indicate that the boride layers are constituted by Fe₂B in either case. It has also been found that with precarburized specimens, the thickness of boride layer has been reduced and its morphology changed to a more flat structure.