强流脉冲离子束辐照对316L不锈钢表面改性的实验研究

利用离子能量为300 keV、束流密度为200 A/cm2、脉冲宽度为75 ns的混合离子束(70%H 30%C )组成的强流脉冲离子束(HIPIB)对316L不锈钢进行了表面辐照处理,辐照次数分别为1,5,10次.采用SEM,XRD,TEM和EPMA分析辐照后试样表面形貌、表面层相组成和微观结构及元素分布的变化.结果表明,HIPIB辐照使试样表面光滑化,表面层晶粒细化、产生择优取向,杂质元素选择性烧蚀,电化学腐蚀性能明显提高.由于HIPIB辐照引起的大应力和冲击波的影响,辐照后在深度达100μm表层内显微硬度提高,表面摩擦系数降低,表面抗磨损性能显著改善.随着辐照次数的增加,316L疲劳极限和蠕变断裂寿命延长,稳态蠕变速率降低.     

强流脉冲离子束辐照WC-Ni硬质合金摩擦磨损行为

利用束流密度50~200 A/cm2、脉冲宽度70 ns的强流脉冲离子束(HIPIB)对WC-Ni硬质合金进行表面辐照处理,测试了辐照WC-Ni硬质合金的微观组织和表面硬度,采用环-块式摩擦磨损试验机、SEM和EDS考察了HIPIB辐照WC-Ni硬质合金的摩擦磨损性能及其磨损机理。结果表明,随束流密度增加,WC-Ni硬质合金表面发生重熔与Ni粘结相的选择性烧蚀,表面重熔致密化,表面硬度显著增加,摩擦系数降低、耐磨性提高,200 A/cm2辐照硬质合金表面熔层约1.6μm,组织明显细化,表面硬度可达14.86 GPa,摩擦系数和磨损率分别降低18%和58%。HIPIB辐照使硬质合金表面磨损机制从原始硬质合金的Ni粘结相优先去除引发WC颗粒剥落去除转变为以均匀微观切削为主的磨粒磨损,这归因于HIPIB辐照WC-Ni硬质合金表面重熔致密化及晶粒细化。     

强流脉冲离子束辐照WC-Ni硬质合金的摩擦磨损性能

为进一步提高WC-Ni硬质合金的表面耐磨性,采用强流脉冲离子束(HIPIB)对其表面进行辐照处理。利用扫描电子显微镜、显微硬度计和环-块式摩擦磨损试验机研究了HIPIB辐照WC-Ni硬质合金的微观组织、硬度分布和摩擦磨损性能。结果表明:HIPIB辐照WC-Ni硬质合金表面发生快速重熔与烧蚀,组织显著细化、致密化;随着束流密度和辐照次数的增加,熔层厚度与硬化层深度增加、摩擦因数和磨损率降低,束流密度300A/cm~2辐照10次,熔层厚度约4μm,硬化层深度可达160μm,摩擦因数和磨损率分别降低45%和70%。辐照硬质合金表面重熔层的磨损主要表现为以均匀微观切削为主的磨粒磨损,近表层冲击硬化区的磨损仍以Ni粘结相的微观磨损和WC晶粒脱落为主,但辐照应力波的长程硬化作用使硬质合金中WC晶粒与Ni粘结相之间的结合力增强以及Ni粘结相自身强化有效抑制了这类磨损。     

强流脉冲离子束辐照改善W9Cr4V轴承钢的表面性能

为改善W9Cr4V轴承钢表面性能,提高轴承使用寿命,研究强流脉冲离子束(HIPIB主要由C+(70%)、H+(30%组成))技术辐照处理效果。用1、10、20、30不同脉冲次数分别对W9Cr4V试片进行处理。采用倒置金相显微镜、X射线衍射仪、显微硬度仪、pin-on-disc(POD)方法、电化学工作站分别测量辐照前后试样的表面形貌和性能。结果表明,HIPIB辐照处理使W9Cr4V轴承钢试片近表层晶粒细化,产生了奥氏体相和碳化物,并且马氏体择优面发生改变,衍射峰向高角方向偏移并宽化。同时,由于HIPIB辐照处理快速升降温和冲击波的影响,处理后试片表面显微硬度最高提高了19.63%,表面耐磨性提高近2倍,耐腐蚀性显著改善。     

强流脉冲离子束辐照WC-Ni硬质密封材料表面改性研究

利用离子能量为300 keV,束流密度为300 A/cm~2,功率密度为10~8W/cm~2,脉冲宽度为70 ns的强流脉冲离子束(HIPIB)对用于核主泵轴密封的WC-Ni硬质合金材料进行了表面辐照处理,辐照次数分别为1,5.10次.利用XRD,SEM和EPMA研究了HIPIB辐照前后WC-Ni硬质合金表层相组成,表面形貌和元素分布的变化.借助显微硬度计和环一块式靡损仪测试了辐照前后硬质合金表层的性能.结果表明,HIPIB辐照硬质合金表层发生由六方碳化物WC向fcc碳化物β-WC_(1-x)转变,转变量随着辐照次数的增加而增加.HIPIB辐照引发硬质合金表层快速重熔和Ni黏结相的择优烧蚀,形成了许多丘状表面凸起,且随着辐照次数的增加,丘状凸起的尺寸增大,当辐照次数增加至10次,形成了网状峰-谷起伏结构的重熔烧蚀表面形貌,且具有微区光滑致密化特征.由于HIPIB辐照应力波的显著作用,辐照后硬质合金表层沿深度方向显著硬化.10次辐照后硬化层深度可达160μm,表面摩擦系数降低38%,耐磨性提高近3倍.     

强流脉冲离子束辐照挤压态AZ31镁合金性能

利用强流脉冲离子束(C+、H+)对变形镁合金AZ31的挤压态靶材分别进行0、1、30和50次辐照试验,分析辐照前后物相组成,检测随辐照次数增加靶材表面的显微硬度,并通过阳极氧化和盐雾试验检测耐蚀性能。结果表明,随HIPIB辐照次数增加,靶材表面显微硬度呈提高趋势,50次辐照表面显微硬度270 HV0.01,较原始靶材的63.7 HV0.01提高了3倍多;极化曲线显示自腐蚀电位和击穿电位提高,自腐蚀电流减小,30次辐照的自腐蚀电位达到-1363 mV,钝化区间为1065 mV;辐照处理后在盐雾试验中形成钝化膜使靶材腐蚀速率显著降低了65%,耐蚀性能得到较大改善。     

强流脉冲离子束辐照W6Mo5Cr4V2高速钢表面改性研究

利用强流脉冲离子束(HIPIB)技术对W6Mo5Cr4V2高速钢进行表面辐照处理，HIPIB主要由C^n (70％)和H^ (30％)组成，束流密度为160A／cm^2，加速电压为250kV，脉冲宽度为80—100ns，能流密度为3—4J／cm^2，脉冲次数分别为1，3和5次,利用XRD，SEM和EPMA研究了HIPIB辐照处理前后该高速钢表面层结构和成分的变化，结果表明，HIPIB辐照处理使该高速钢表面层发生由马氏体α′-Fe向奥氏体γ-Fe转变，其表面产生许多火山口状熔坑，熔坑中心处富含离子束元素成分，熔坑的形成可以用“雨滴”模型进行解释,由于HIPIB辐照压缩波的影响，处理后在深度达200μm左右的范围内该高速钢的显微硬度提高，表面层耐磨性能提高近2倍，而且耐腐蚀性能也有所提高。     

W6Mo5Cr4V2钢表面强流脉冲离子束辐照研究

利用扫描电镜(SEM)、台阶仪、X射线衍射仪(XRD)、透射电镜(TEM)、显微硬度仪对W6Mo5Cr4V2钢经强流脉冲离子束(HIPIB)辐照前后试样的表面形貌、粗糙度、表层的组织结构及硬度进行了分析,探讨了"熔坑"和硬度"多峰"态形成的原因.结果表明,试样表面粗糙度随辐照次数的增加有所减小;辐照过程使该钢体心立方的马氏体α'-Fe向面心立方的奥氏体γ-Fe转变,碳化物溶解,马氏体溶碳量增大且晶粒细化,点阵畸变度增大,使W6Mo5Cr4V2钢表面硬度有较大的提高.     

金属材料表面强流脉冲离子束辐照强化

介绍了TEMP型强流脉冲离子束(HIPIB)装置及其工作原理。总结了HIPIB辐照不同金属材料表面后的硬度、耐磨性和耐蚀性的试验结果。HIPIB的瞬间高能量密度沉积导致金属表面快速加热冷却，产生显著的热-力学效应。辐照表面发生的细晶强化、加工硬化和相变强化，使金属材料在较大的深度范围(约100μm)内硬度提高，耐磨性改善；同时，辐照表面金属成分纯净化和组织结构均匀化，有利于提高金属材料耐蚀性。     

强流脉冲离子束对TiAlN涂层刀具的表面改性

采用强流脉冲离子束辐照的改性方法研究了其对Ti Al N涂层刀具的表面改性效果。使用1.5、2.3 J/cm2的强流脉冲离子束对试样进行1、5、10次辐照实验。结果表明,试样表层产生大量龟裂状裂纹。随着辐照次数和脉冲能量的增加,试样表层微裂纹逐渐减少,取而代之的是沸腾状的烧蚀孔洞。辐照后,试样的表面显微硬度和耐磨性均得到了提高,试样的表面显微硬度最高提高了24.9%,耐磨性最高提高了25.5%。     

Wear mechanism of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam

The wear resistance and wear mechanism of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam (HIPIB) at an ion current density of 100 A/cm² with shot number from one to ten are investigated by dry sliding wear tests. The cross-sectional microstructure and surface microhardness of the irradiated AZ31 magnesium alloys are examined by optical microscopy (OM) and Vickers tester, respectively. It is found that surface hardness increased with increasing shot number, from an original value of 570 MPa to a maximal value of 820 MPa with ten shots, and the wear rate of the samples irradiated with five and ten shots was about one order of magnitude less than that of the original sample. The transition from severe metallic wear to mild oxidative wear induced by HIPIB irradiation was identified through a combined analysis in surface morphology and chemical composition of wear tracks, mechanically mixed materials, wear debris and wear scars of counterface steel ball by using scanning electron microscopy (SEM) and electron probe microanalysis (EPMA), which is mainly attributed to the significant increase in microhardness resulting from grain refinement on the irradiated surface.     

Wear and corrosion properties of laser cladded Cu47Ti34Zr11Ni8/SiC amorphous composite coatings on AZ91D magnesium alloy

To improve the wear and corrosion properties of AZ91D magnesium alloys, Cu-based amorphous composite coatings were fabricated on AZ91D magnesium alloy by laser cladding using mixed powders of Cu47Ti34Zr11Ni8 and SiC. The wear and corrosion behaviours of the coatings were investigated. The wear resistance of the coatings was evaluated under dry sliding wear condition at room temperature. The corrosion resistance of the coatings was tested in 3.5% （mass fraction） NaCl solution. The coatings exhibit excellent wear resistance due to the recombined action of amorphous phase and different intermetallic compounds. The main wear mechanisms of the coatings and the AZ91D sample are different. The former is abrasive wear and the latter is adhesive wear. The coatings compared with AZ91D magnesium alloy also exhibit good corrosion resistance because of the presence of the amorphous phase in the coatings.     

磁控溅射镀钛提高 AZ31 镁合金耐磨耐蚀性能的研究

目的提高AZ31镁合金的耐磨及耐腐蚀性能。方法采用磁控溅射技术对镁合金进行表面镀钛处理,用扫描电镜研究膜基界面形貌及界面成分,分析结合性能。通过摩擦磨损试验,对比分析镁合金基体和镀Ti膜样品的耐磨性能;通过Tafel极化曲线,对比分析镁合金基体和镀Ti膜样品的耐蚀性能。结果 Ti膜均匀致密,与镁合金基体结合良好。镁合金镀Ti膜后,摩擦系数和磨损失重率下降,腐蚀电位向正方向移动了430 m V,腐蚀电流密度从10.83 m A/cm2下降到2.62×10-7m A/cm2。结论磁控溅射镀Ti膜提高了AZ31镁合金的耐磨和耐蚀性能。     

AZ31镁合金表面强流脉冲电子束铝合金化研究

利用强流脉冲电子束对AZ31镁合金表面进行快速铝合金化,分析了表面合金化层的显微结构,测量了铝合金化前后,AZ31镁合金的腐蚀性能与耐磨性能.结果表明,经电子束轰击后表层出现了典型的熔坑形貌;耐磨性能测试表明,加速电压为27 kV,脉冲5次的试样比原始试样的相对耐磨性提高6倍,同时合金化也提高了在5%的NaCl溶液中的耐腐蚀性能.     

强流脉冲离子束辐照镁合金微弧氧化膜的耐腐蚀性能

采用强流脉冲离子束在束流密度为200 A/cm2、辐照次数为1~10次条件下对AZ31镁合金微弧氧化膜进行辐照改性处理。采用扫描电子显微镜对氧化膜的表面及截面形貌进行表征;在Princeton Applied Research(PAR)2273型电化学工作站测量氧化膜的极化曲线。结果表明:在束流密度200 A/cm2、5次辐照条件下氧化膜表面获得连续、致密的改性层;以3.5%NaCl溶液为腐蚀液,氧化膜表面发生的腐蚀过程由辐照前的活化溶解向辐照后的钝化-孔蚀击穿转变;在束流密度200 A/cm2、5次辐照条件下击穿电位提高到最大值-800 mV(vs SCE)。强流脉冲离子束辐照产生的连续致密改性层是氧化膜耐蚀性改善的主要原因。     

AZ31B镁合金盐浴碳氮钒共渗工艺

为提高AZ31B镁合金的表面硬度,改善其摩擦磨损性能及耐蚀性能,采用盐浴碳氮钒共渗工艺在AZ31B镁合金表面形成高硬度碳、氮化合物渗层,并用数字显微硬度计、光学显微镜、X射线衍射仪、X射线能谱仪、摩擦磨损试验和电化学测试分析渗层表面硬度、截面显微形貌、渗层表面物相组成、耐磨性和耐蚀性等。结果表明,盐浴碳氮钒共渗处理使AZ31B镁合金表面形成主要由VC、VN等高硬度金属化合物组成的渗层,渗层表面硬度最高达到283.1 HV0.05,相比原始试样和碳氮共渗处理试样分别提升280%和62%;相比原始试样,碳氮钒共渗试样的摩擦因数和磨损量分别降低约30%和50%,自腐蚀电位提高60 mV,自腐蚀电流密度降低一个数量级,表明盐浴碳氮钒共渗工艺能够显著提高AZ31B镁合金的表面硬度,提升其摩擦磨损性能及耐蚀性能。     

Improving wear resistance and corrosion resistance of AZ31 magnesium alloy by DLC/AlN/Al coating

A novel protective coating, consisting of three layers (top: diamond-like carbon, middle: aluminum nitride, bottom: aluminum), was deposited on the surface of AZ31 magnesium alloy layer by layer. Nano-indenter, electrochemical system and tribological tester were performed to investigate the hardness, wear resistance and corrosion resistance of the coated AZ31 magnesium alloy, respectively. The DLC/AlN/Al coating improved the magnesium alloy's surface hardness and reduced its friction coefficient, which consequently induced a great improvement of the magnesium alloy's wear resistance. Furthermore, the corrosion resistance of the AZ31 magnesium alloy with the DLC/AlN/Al coating was also enhanced with the corrosion current density decreasing from 2.25 × 10⁻⁵ A/cm² to 1.28 × 10⁻⁶ A/cm² in a 3.5 wt.% NaCl solution.     

Wear behaviour of hot rolled AZ31B magnesium alloy as candidate for biodegradable implant material

Surface integrity and tribological behaviour of implant materials have a critical impact on their performance in the body. To understand wear behaviour well, the present article focuses on the sliding wear behavior of hot rolled AZ31B magnesium alloy which is a good candidate for biodegradable implant material. Dry-sliding conditions which include pin-on disc method with heat-treated high-carbon steel disc as counterface were used. Wear rates at a fixed sliding distance of 5000 m were measured at sliding velocities of 0.25, 0.5, 1 and 2 m/s, and loads of 10, 20, 40 and 80 N. Microstructure of worn surfaces of pins was characterized using SEM/EDS. Wear mechanism maps of the investigated materials were composed to understand comprehensively. According to test results, abrasive wear occurred at load of 20 N and sliding speed of 0.25 m/s while melting wear was predominant at load of 80 N and sliding speed of 2 m/s. Results show that ultra-severe plastic deformation is the main wear mechanism at the highest applied load and sliding velocity speed for the investigated alloy. Consequently, hot rolled AZ31B magnesium alloy exhibited a good wear resistance due to fine microstructure and high hardness.     

Effect of Hot Extrusion on Microstructures and Properties of TiB2/AZ31 Magnesium Based Composites

采用原位合成-半固态搅拌铸造法制备了TiB2/AZ31镁基复合材料,研究了热挤压对TiB2/AZ31镁基复合材料组织和力学性能的影响。结果表明：热挤压不仅能显著细化合金组织,而且能有效改善TiB2颗粒分布的均匀性。与铸态AZ31镁合金相比,铸态TiB2/AZ31镁基复合材料的硬度、抗拉强度都有一定程度的提高。经过热挤压后,TiB2/AZ31镁基复合材料的硬度和抗拉强度分别比基体合金提高了126.2%和98.8%,达到950 MPa和322 MPa。磨损表面形貌显示,TiB2颗粒的引入以及对TiB2/AZ31镁基复合材料进行热挤压,都可有效地提高材料的耐磨性。     

Corrosion and wear resistance of AZ31 Mg alloy treated by duplex process of magnetron sputtering and plasma electrolytic oxidation

In order to improve the wear and corrosion resistance of AZ31 magnesium alloy, a magnetron-sputtered Al layer with a thickness of 11 μm was firstly applied on the alloy, and then treated by plasma electrolytic oxidation (PEO) in an aluminate and silicate electrolytes, respectively. The performance of PEO coatings was investigated by dry sliding wear and electrochemical corrosion tests. The aluminate coating exhibits excellent wear resistance under both 10 and 20 N loads. The silicate coating only shows low wear rate under 10 N, but it was destroyed under 20 N. Corrosion tests show that the Al layer after magnetron sputtering treatment alone cannot afford good protection to the Mg substrate. However, the duplex layer of PEO/Al can significantly improve the corrosion resistance of AZ31 alloy. Electrochemical tests show that the aluminate and silicate coatings have corrosion current densities of ∼1.6×10⁻⁶ and ∼1.1×10⁻⁶ A/cm², respectively, which are two orders lower than that of the un-coated AZ31 alloy. However, immersion tests and electrochemical impedance spectroscopy (EIS) show that the aluminate coating exhibits better long-term corrosion protection than silicate coating.