Nanoindentation behavior of molybdenum surface-modified titanium

By using double glow plasma surface metallurgy technique, the molybdenum (Mo) surface-modified layer on titanium (Ti) was obtained. The corresponding cross-section morphology, phase formation, and element concentration were investigated by optical microscopy, X-ray diffraction (XRD), and glow discharge optical emission spectroscopy (GDOES), respectively. The experimental results indicate that the Mo modified layer is composed of a 1.7 μm pure Mo deposition layer and a 14.3 μm Mo diffusion layer. Along the sample thickness direction, nanoindentation tests were performed on the cross-section of the Mo diffusion layer and the Ti substrate (for the comparison purpose) by Hysitron TI900 TriboIndenter. The 2D and 3D residual indentation profiles of the Mo diffusion layer were obtained by scanning probe microscopy (SPM). The elastic modulus and hardness values of every indent were acquired and analyzed. According to the load-displacement curves, the plastic deformation degrees of the Mo diffusion layer and the Ti substrate were analyzed. It is indicated that the Mo diffusion layer possesses high strength-toughness.     

Effect of infiltrating Si on friction properties of C/C composites

In order to improve the friction-wear properties of the C/C composites for aircraft brake pairs, the friction behavior of samples with infiltrating Si was investigated. The influence of Si smearing thickness on friction properties was studied in detail. The results show that with the increase of Si smearing thickness and β-SiC content, the friction coefficient reduces from 0. 40 to 0. 30; the linear wear of stators increases from 2. 0 μm to 18. 9 μm per cycle, and that of rotors increases from 1. 4μm to 22. 6 μm per cycle; mass wear of stators increases from 20. 6 mg to 126. 9 mg per cycle, and that of rotors increases from 13. 7 mg to 166. 2 mg per cycle. On the other hand, when a large number of inhomogeneous β-SiC particulates are performed, friction surfaces of the samples flake off layer by layer and many nicks are observed.     

基于细化分层法探讨面波频散曲线反演参数的简化

常规频散曲线反演过程中需要不停地改变分层数、层厚度和层速度等参数,实现过程相对繁琐,而采用细化分层法对反演参数进行简化则避免了上述缺点。具体思路为:根据目的层探测深度(如20m)将地下介质分为若干个(20个)厚度为1m的薄层和1个均匀半空间层(共21层),这样在反演中分层数和层厚度均为已知参量,反演过程只需修改速度参数即可,避免了改变分层数和层厚度等参数,显著简化了反演计算过程。正演计算和反演结果均表明:细化分层与实际分层计算出的频散曲线是等效的,细化分层反演结果的总体效果与真实模型非常接近,这说明细化分层方法用于频散曲线反演是切实可行且有效的;将地下介质划分为1m厚的薄层,反演后每层均可得到1个横波速度,能满足反演分辨率的要求;由于实际地下介质的速度是随深度渐变的,细化分层后比按频散曲线拐点分层(每分层的厚度可能是几米或几十米,同一分层内介质的横波速度相等)更接近实际情况。     

Microstructure and properties of nitrided layer of titanium plate,produced by simultaneous laser quenching and liquid-nitrogen cryogenics

In the present study, titanium plate was treated by a novel method of laser quenching, simultaneously combined with liquidnitrogen cryogenics(LQLNC). The microstructure and properties of the titanium plate after treatment were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, Vickers hardness testing, and friction wear testing.The results show that the treated titanium plate is covered by a nitrided layer with a homogeneous thickness of about 60 μm,while the nitrided layer consists of Ti N and α-Ti phases. Compared to general laser quenching, the LQLNC treatment increases the hardness and wear resistance of the surface-modified layer of the titanium plate. As a result of grain refinement in the nitrided layer, the cracking induced by the rapid solidification of the conventional laser-quenching process has also been effectively solved.     

等离子堆焊原位合成WC增强Ni基合金改性层

为了进一步提高Ni基合金的耐磨性能,采用等离子堆焊技术在304L奥氏体不锈钢表面原位合成WC增强Ni基合金改性层.利用光学显微镜、扫描电子显微镜和能谱仪、X射线衍射仪、显微硬度计及销-盘磨损试验机等设备对改性层的显微组织、成分、显微硬度及摩擦磨损性能进行研究.结果表明:当Ni基合金改性层中直接加入WC颗粒时,WC颗粒出现"沉底"现象,改性层组织不均匀,而通过原位反应合成的WC相呈块状弥散分布于整个改性层,加入适量的氧化钇后,改性层组织变得细小致密,WC增强相的形态、尺寸和分布等均发生了变化,改性层硬度显著提高,耐磨性提高了2倍以上.     

高能脉冲冷焊Fe基合金改性层的组织及性能

为了进一步提高核泵用钢的耐磨性能及抗空蚀性能,采用高能脉冲冷焊技术在304不锈钢表面制备了Fe基合金改性层.利用扫描电子显微镜和X射线衍射仪分别对改性层的显微组织和相结构进行了分析,利用显微硬度计、摩擦磨损试验机及超声波振荡空蚀仪分别对改性层的显微硬度、耐磨性与抗空蚀性能进行了研究.结果表明,改性层组织细密,且主要由基体相α-Fe和硬质碳化物相Cr_(23)C_6和Cr_7C_3组成,改性层的最高显微硬度可达510 HV,相对耐磨性为3.88.空蚀5 h后,改性层的失重量和表面粗糙度分别约为304不锈钢基材的1/5和1/6.     

碳氮共渗钢干摩擦状态下磨损行为的研究

对20#钢试样进行C-N共渗热处理,经C-N共渗的试样进行干摩擦磨损试验,实验的载荷为2N到6N,滑动速度从8m/s到45m/s.摩擦磨损试验表明在滑动速度为35m/s左右时,发生了从轻微磨损向严重磨损的转变,结合SEM、AES和XPS分析,磨损率的变化与磨损表面的氧化物形成与剥落、氧化物的类型转变(Fe2O3转变成FeO)有密切关系.     

Friction and Wear Behavior of Modified Layer Prepared on Ti-13Nb-13Zr Alloy by Magnetron Sputtering and Plasma Nitriding

Two kinds nitride modified layers were obtained on Ti-13Nb-13 Zr surface to improve the wear property via magnetron sputtering and plasma nitriding techniques, respectively. The structures of the modified layer and the worn surface after sliding test were characterized using X-ray diffraction(XRD) and scanning electron microscopy(SEM). The friction and wear behavior of the modified layer against alumina ball was investigated in the absence of lubricant under different loads(1 N and 2 N). The X-ray diffraction analysis reveals that nitride layer is mainly composed of TiN and Ti_2N, while coating film consists of Ti N phase. Friction and wear test indicates that both modified layers can improve the wear resistance compared to untreated Ti-13Nb-13 Zr. Ti N thin film produces very hard surface, but may be easy to cause coating fracture and delamination under high normal load. However, nitride layer exhibits better wear performance. This is attributed to hard compound layer maintained its integrity with the hardened nitrogen diffusion zone during friction and wear process.     

α-Al2O3载体上NaA型分子筛膜的制备及表征

采用原料配比SiO2∶Al2O3∶Na2O∶H2O=2∶1∶8.9∶700制备了粒径为6μm的NaA沸石晶种.利用二次生长法在微孔α-Al2O3载体管外表面制备NaA型分子筛膜,通过SEM和XRD对制备的分子筛膜进行了结构表征,并对其气体渗透性能进行了测试.结果表明,重复合成3次后,在3μm孔径载体表面形成了一层致密、连续的沸石晶体层,沸石膜厚约20μm;N2的渗透率为5.8×10-5 mol/(m2.s.Pa),氧氮分离系数为1.3左右,大于相应的努森扩散系数0.94,说明制备的分子筛膜有一定的筛分作用.     

Microstructure and Wear Behavior of Ti-6Al-4V Treated by Plasma Zr-alloying and Plasma Nitriding

A duplex treatment of plasma Zr-alloying and plasma nitriding was used to improve the tribological properties of Ti-6Al-4V. The microstructure of the Zr-N composite(alloyed) layer formed on Ti-6Al-4V and its hardness, friction and wear properties were investigated by using OM, SEM, GDOES, EDS, microhardness tester as well as ball-on-disk tribometer. The results of microstructural analysis show that the alloyed layer is compact and uniform and is mainly composed of ZrN, TiN_(0.3) and AlN. A very tiny adhesive and slight oxidation wear is the primary wear mechanism for the modified Ti-6Al-4V. The tribological property is improved significantly after the duplex treatment. The good combination of antifriction and wear resistance for modified Ti-6Al-4V is mainly attributed to the higher surface hardness of metal nitrides formed on the surface and enhanced supporting of the Zr-diffusing layer.     

表面滚压强化A473M钢的组织及性能

为了提高A473M马氏体不锈钢表面的耐磨性能,采用滚压加工强化不锈钢表面,对其组织及性能进行研究,并确定了最佳工艺参数.采用扫描电子显微镜、白光干涉仪、显微硬度计和摩擦磨损实验机对不锈钢的硬化层组织、表面粗糙度、显微硬度及摩擦磨损性能进行表征.结果表明,当滚压进给量由0.05 mm/r增加至0.15 mm/r时,不锈钢表面粗糙度变化趋势呈“∨”形,表面显微硬度和磨损性能的变化趋势呈“∧”形.当进给量为0.1 mm/r且表面粗糙度为62.7 nm时,不锈钢硬化层组织明显细化,滚压层表面显微硬度达到550 HV且为基材的2.2倍,硬化层深度达到200 μm,相对耐磨性为3.7.     

经激光表面熔凝处理的Mg-11Y-2.5Zn合金的显微组织和摩擦学性能

用X-ray衍射和激光共聚焦扫描显微镜对经激光表面熔凝处理的Mg-11Y-2.5Zn合金进行显微组织和相组成分析,并测量改性层硬度变化。研究结果表明,经激光表面熔凝处理后,改性层由熔化区和热影响区组成,熔化区的显微组织明显细化,硬度有所改善。研究了经激光表面处理和铸态Mg-11Y-2.5Zn合金的摩擦学性能,滑移速率为0.785m/s,载荷范围为20～320N。两者的摩擦因子无显著差异,但经激光表面处理的Mg-11Y-2.5Zn合金表现出较低的磨损率,归结于熔凝区的组织细化和硬度增加。SEM磨损表面形貌分析表明,激光表面熔凝处理的合金与未处理合金的磨损机制基本相同,轻微磨损阶段为磨粒磨损和剥层磨损,严重磨损阶段为表面热软化和熔化磨损。     

3%无取向硅钢薄板的表面纳米化结构与性能

为了探索金属薄板表面纳米化制备方法,本工作选取3%无取向硅钢热轧板进行表面机械研磨处理（SMAT）和异步轧制（CSR）,研究深度方向结构和硬度的变化.结果表明：SMAT过程中,3%无取向硅钢通过位错的演变,在表面形成了等轴状、尺寸约为10 nm的、取向呈随机分布的纳米晶,纳米晶层厚度约为20μm;SMAT样品经过CSR后,表面的显微组织基本不变,但纳米晶层的厚度明显减小;SMAT和CSR处理使表面硬度显著提高（约为85%）.本工作表明,SMAT与CSR复合工艺可以制备大尺寸的、具有纳米结构表层的金属薄板.     

TiC涂层梯度硬质合金残余热应力分析

采用有限元方法分析有无梯度2种TiC涂层硬质合金的残余热应力,研究了残余应力随涂层及梯度层厚度的变化。结果表明:增加梯度层后,涂层内残余热应力的减小超过10%,合金中残余应力减小30%以上,表面残余应力也明显下降;随着涂层厚度的增加,涂层内拉应力大幅减小,剪切应力与等效应力略微增加,涂层梯度硬质合金的等效应力呈下降趋势;随着梯度层厚度的增加,涂层内残余应力减小,当梯度层厚度较大时,残余应力不再改变。因此,选择合适的涂层和梯度层厚度,涂层厚度一般为5～8μm,梯度层厚度控制在20μm左右,可以有效缓和残余应力,提高材料的结合强度。     

Microstructures of NiFe/nonmagnetic metal spacer/FeMn films and their influences on exchange coupling

The discovery of the oscillatory exchange coupling between ferromagnetic (FM) layers separated by a nonmagnetic spacer layer in 1986[1] aroused peoples interest in the magnetic prop-erties of metallic multilayered films. FM/ nonmagnetic metal spacer /FM systems with any of the 3d transition metals Fe, Co and Ni or their alloys as FM material have been systematically stud-ied[24]. Oscillatory exchange coupling via spacers has been known as a general phenomenon relevant to many spacer materi…     

低温电解磁化渗硫工艺及减摩特性的研究

采用外加磁场对碳氮共渗的20CrMnTi钢进行磁化低温电解渗硫处理,着重探讨了磁化低温电解渗硫工艺的影响因素,特别是添加剂和磁化作用的影响,进而优化工艺参数,并利用摩擦磨损试验研究该渗硫层的减磨特性.结果表明,添加剂K3Fe（CN）6有效降低盐浴粘度,提高电导;外加磁场改善了电解质的分散能力,提高盐浴的电导和稳定性,促进渗硫过程的进行,延长盐浴寿命.外加磁场的低温电解渗硫最佳工艺参数为电流密度0.2 A/dm2,外加磁感应强度0.07 T,添加剂1％K3Fe（CN）6,温度190℃,时间15 min.获得20 μm左右厚度均匀的渗硫层,明显降低摩擦系数并显著提高了工件的抗磨损和抗咬合能力.     

WC/Cu-Zn-Mn 强化中碳钢高耐磨表层复合材料

采用熔浸复合法制备了ＷＣ／Ｃｕ Ｚｎ Ｍｎ强化中碳钢表层复合材料,探讨了ＷＣ粒度、熔浸复合温度等工艺因素对复合材料组织与性能的影响。研究结果表明,在两体静载磨料磨损工况下,新型表层复合材料的耐磨性是中碳钢基体的２６倍,是水韧高锰钢的２０倍,且可根据需要调节复合层厚度,故可在很大范围内替代整体耐磨材料,是一种有实用价值的高耐磨表层复合材料。     

三相流化床中载休表面生物膜形成与膜厚影响因素实验研究

实验研究了内导流筒式三相好氧生物流化床处理低浓度废水时高分子载体表面生物膜的形成条件以及操作条件对生物膜厚度的影响。实验结果表明,在水力停留时间2.5～3h,有机容积负荷6.01～7.08kgCOD/(m3     

纳米填料增强UHMWPE–橡胶水润滑摩擦学性能

为了研究水润滑条件下试验载荷和速度对纳米填料（Nano-SiC）改性超高分子量聚乙烯（UHMWPE）/橡胶复合材料摩擦学性能的影响,通过高温混炼、热压成型制备Nano-SiC辅以聚四氟乙烯（PTFE）填充改性UHMWPE/橡胶复合材料。采用MRH-3型环-块摩擦实验机探究四种不同载荷条件下改性复合材料的摩擦磨损性能,采用光学显微镜（OM）、扫描电子显微镜（SEM）和非接触光学三维轮廓仪对试样微观磨损表面形貌分析,从微观层面探究改性复合材料的摩擦机理。试验结果表明：在定载变速条件下,速度由0.02m/s升到3.59m/s时,改性复合材料的动摩擦系数波动幅度与静摩擦系数均呈现大幅下降趋势,粘-滑现象（Stick-Slip Phenomenon）减弱,摩擦系数波动归于平稳;试验载荷和纳米粒子含量的变化与试样摩擦磨损程度呈负相关,在水润滑条件下,随着纳米粒子含量增加,摩擦系数与磨损率均出现明显降低,填充比例为5%的复合材料摩擦学性能最佳,摩擦系数整体较UHMWPE/橡胶材料降低35%,磨损率降低46.6%,磨损表面形貌也随之发生改变;随着载荷的增加,复合材料的磨损率从1.25×10-6mm3/(Nm)降至0.4×10-6mm3/(Nm)。Nano-SiC的含量与工况载荷压力对摩擦磨损均存在一定影响,即填充适量Nano-SiC的UHMWPE/橡胶复合材料与一定工况压力下的对偶钢环组成的摩擦配副能改善摩擦环境,减轻粘-滑现象,有利于减小材料的磨损。     

激光功率参数对GCr15钢组织和抗磨性能的影响

为研究不同激光功率参数对激光硬化后的最终显微组织、硬度和耐磨性的影响,应用宽带扫描技术进行了GCr15轴承钢激光强化处理试验,用光学显微镜和扫描电镜、x射线衍射仪等现代测试手段对GCr15轴承钢试样的显微组织和形貌尺寸特征进行了分析,磨损试验在MM200磨损试验机上进行.结果表明,激光参数变化所产生的显微组织变化造成了表面硬度值和磨损率的较大差异.激光功率大时,激光硬化层表面未溶碳化物量减少,使得表面马氏体中碳的质量分数增加,表面硬度增高.在干摩擦磨损过程中,激光改性层表面发生摩擦诱发马氏体相变.在干摩擦和油润滑两种条件下,激光功率越大,激光硬化层的抗磨损性越好.