自熔性合金粉末喷熔层的研究

通过对４种常用自熔性合金粉末喷层的磨料磨损试验和三酸一盐介质中的腐蚀试验，探讨了若干因素喷熔层耐磨性和耐蚀性的影响。     

几种火焰喷焊自熔性合金层的耐磨性能

研究了不同自熔性合金粉末火焰喷焊层的显微组织与抗磨粒磨损性能，并对其磨面形貌进行了ＳＥＭ观察分析。结果表明，在Ｎｉ６０自熔性合金中加入适量的镍包ＷＣ粉末可明显提高其喷焊层的抗磨粒磨损性能。当ＷＣ的加入量为３５％（ｗｔ）左右时，该喷焊层与６０Ｓｉ２Ｍｎ调质钢相比，相对的耐磨性可提高６倍以上。     

热喷焊镍基自熔性合金（NiO2）涂层的耐磨性及组织研究

采用Ｘ－射线衍射仪，等，分析研究了氧乙炔火焰焊接基自熔性合金粉末涂层的组织及其结构，硬质相的形貌及分布，涂层的磨损性能磨损规律，探讨了涂层具有高耐磨性的原因。     

等离子喷焊铜基自熔性合金的研制

为了克服铜铁异种材料喷焊过程中易产生焊缝裂纹和基体裂纹的倾向,研制开发了一种Cu-Ni-Sn自熔性合金粉末材料.通过对Cu-Ni-Sn粉末材料的化学成分的设计,喷焊层的组织显微结构及抗腐蚀性能的综合分析,认为该材料等离子喷焊工艺性能良好,焊层耐腐蚀效果十分明显.在生产实际中应用等离子喷焊制备Cu-Ni-Sn焊层,能明显提高粉末材料的熔敷率和性能,并且改善劳动工作环境.该合金性能优于传统材料,值得推广.     

WC加入量对Ni60自熔合金喷焊层冲蚀磨损特性的影响

在转盘式磨蚀试验台上,对Ni60 25%WC和Ni60 35%WC涂层进行了冲蚀磨损试验,结果表明:在加入量25%～35%范围内,WC加入量的变化对涂层的耐冲蚀性能的影响不大,两种涂层的冲蚀磨损机理主要是微切削.     

镍、铁基喷焊层组织与性能研究

为寻找具有耐盐酸腐蚀能力的喷焊用合金粉末,自行设计了3种喷焊粉末,并对比研究了自制粉末与商业Ni60粉氧乙炔喷焊层的显微硬度、显微组织形貌和耐盐酸腐蚀性能.结果表明,自制1号粉喷焊层的显微硬度值明显高于商业Ni60喷焊层,自制2号粉喷焊层的显微硬度和耐蚀性均优于商业Ni60喷焊层.分析认为,钼的加入可改善合金粉末的喷焊工艺性,提高喷焊层的耐盐酸腐蚀性能;铬含量的增加显著提高了喷焊层的显微硬度;喷焊层中铁含量的增加对耐盐酸腐蚀性能有不利影响.     

激光熔覆与等离子喷焊WF218合金的组织和性能比较

气门密封面激光熔覆的工艺和性能研究较多,但激光熔覆的合金组织和性能与现在气门密封面生产应用的等离子喷焊合金的对比数据较少.为了推动激光熔覆技术在气门密封面生产中的应用,对目前应用的气门WF218合金进行了激光熔覆层与等离子喷焊层的对比研究.通过对同炉气体雾化生产的WF218合金粉末分别进行激光熔覆和等离子喷焊,对两者合金层研究结果显示,激光熔覆合金层更致密、组织更细小、成分更均匀、耐蚀性和耐磨性更好.根据研究数据,激光熔覆技术应用于气门密封面生产将进一步提高质量.     

机械镀Zn-Al合金镀层的耐腐蚀性能研究

为了增强机械镀镀层的耐腐蚀性能,采用机械镀方法,以含铝5%(质量分数)的Zn-Al合金粉为原料,在Q235钢材基体表面制备了Zn-Al合金镀层。利用扫描电镜(SEM)表征了合金镀层的截面和断面形貌;采用极化曲线、电化学阻抗谱(EIS)分析了合金镀层在3.5%NaCl溶液中的电化学行为;通过中性盐雾腐蚀实验分析了合金镀层的耐蚀性,并采用XRD分析了镀层的盐雾腐蚀产物。结果表明,Zn-Al合金镀层由葫芦状的Zn-Al合金颗粒交错互嵌堆积而成,镀层颗粒之间以类似隼接的连接方式搭接“卡锁”;与机械镀Zn层相比,Zn-Al合金镀层的腐蚀电位正移了209 mV,腐蚀电流密度仅为纯Zn镀层的7.1%左右,极化电阻为纯Zn镀层的14倍;Zn-Al合金镀层的容抗弧半径明显大于纯Zn镀层的弧半径,且Q_dl较纯锌层减小;纯Zn镀层出现白锈和红锈的时间分别为24和362 h,而Zn-Al合金镀层出现白锈和红锈的时间为48和504 h。Zn-Al合金镀层的耐中性盐雾腐蚀性能明显优于纯Zn镀层,合金镀层对电荷转移具有更好的抑制作用,且Zn-Al合金镀层的腐蚀产物结构致密,可增强物理屏蔽功能。     

低温时效对Fe-22Al合金微观组织和力学性能的影响

利用金相显微镜、XRD、TEM和力学性能测试方法研究了低温时效对Fe-22Al合金的微观组织和力学性能的影响。结果表明,Fe-22Al合金经退火和固溶处理后的金相组织为粗大的等轴状晶粒,但固溶处理后晶粒尺寸有所减小。合金主要的相组成为α-Fe相以及具有B2结构的FeAl相,不存在DO3结构的Fe3Al相。存在明显的基体衍射斑点和(100)超点阵斑点意味着发生失稳有序化转变,并形成大量B2结构的有序相。暗场像结果表明存在大量Al原子的富集区和贫集区,即合金中发生了调幅分解转变。经过530℃时效处理后,合金的衍射斑点中同时存在DO3结构和B2结构的超点阵斑点。随时效的进行,逐渐发生B2→DO3相变,在B2结构的有序相内部形成大量细小的DO3相,并逐渐长大和粗化,最终形成粗大的海绵状结构。经过固溶和时效处理后,Fe-22Al合金的硬度和抗压强度分别为359HV、1610 MPa。     

Fe-33Ni-4Co-1.2Nb超低膨胀合金研究

研究了一种雷达天线罩连接环用Fe-33Ni-4Co-1.2Nb低膨胀合金,该合金具有极低的膨胀系数(α20～100℃0.9×10-6/℃),同时,该合金也具有良好的机械力学性能和加工性能,试验表明,该合金较好地解决了天线罩与基体的连接问题,是制作天线罩连接环和其它需要低膨胀封接的良好材料。     

Study on corrosion resistance of aluminium coating deposited on magnesium-zinc-yttrium-calcium alloy by cold spray

Pure aluminium coatings were prepared on magnesium-zinc-yttrium-calcium alloy substrate via cold spraying technology with different scanning speeds and working gas temperature. The correlation between the corrosion resistance of the coatings and the different spraying process was studied. While the working gas temperature is 600 °C and the scanning speed is 1 mm/s, aluminium coating has less porosity and the coating was well combined with the substrate. Higher temperature of working gas increases the plastic deformation of particles, which lead to a dense aluminium coating. The relationship of corrosion resistance on working gas temperature and scanning speed of aluminium coatings has also been investigated by immersion corrosion test and electrochemical impedance spectroscopic techniques. The results show that the cold sprayed aluminium coatings revealed a lower porosity and higher corrosion resistance with the decreasing scanning speed and the increasing temperature of working gas. The porosity and corrosion current densities were 0.938 vol.% and 2.427 ⋅ 10⁻⁶ A/cm². The experimental results show that the aluminium coating prepared by cold spraying has a good protective effect on magnesium alloy.     

Effect of Cu content on microstructure and properties of Fe-16Cr-2.5Mo damping alloy

Five Fe-16 Cr-2.5 Mo damping alloys with different Cu contents(0%,0.25%,0.5%,1.0% and 2.0%) were prepared.The microstructure was observed by scanning transmission electron microscopy(STEM) and the damping behavior was measured by using a dynamic mechanical analyzer(DMA).The results show that the grain size of experimental alloy with(0.25–1.0%) Cu was refined compared with the 0 Cu alloy.The Cu element is fully dissolved in the matrix and there are no Cu precipitates and carbides observed.Although the internal stress increases because of Cu addition,the damping capacity of the 0.5 Cu and1.0 Cu alloys has been significantly improved.The reason of damping improvement is that the magnetic domain structure is strongly modified.Meanwhile,the strength was improved gradually due to the Cu solid solution strengthening and grain refining.In the 2.0 Cu alloy,lots of Cu-riched particles appeared in the matrix.These Cu precipitates with 10–15 nm in size are spherical and homogeneously distributed,which strongly induce strength improvement through precipitation strengthening.On the contrary,the elongation and impact energy of the 2.0 Cu alloy decrease sharply.In addition,lots of Cu precipitates will significantly decrease the damping capacity by hindering the mobility of domain walls.     

Diffusion bonding of Fe-28Al(Cr) alloy with low-carbon steel in vacuum

Fe-28Al(Cr) alloy and low-carbon steel were diffusion bonded in a vacuum of 10⁻⁴-10⁻⁵ Pa. The relationship of the bond parameters and shear strength at the interface was discussed. Microstructure characteristics and the reaction products at the interface were investigated by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The thickness of the diffusion reaction layer was measured with electron probe microanalysis (EPMA). The results indicated that controlling bonding temperature 1333 K for 3.6 ks, shear strength at the interface can be up to 112 MPa. Three kinds of reaction products were observed to have formed during the vacuum diffusion bonding, namely FeAl, Fe₃Al and α-Fe (Al) solid solution. The thickness (X) of the diffusion reaction layer increases with bonding time (t) according to a parabolic law X²=6.4×10³ exp(−104.1/RT)(t-t₀) (μm²).     

PVD法渗Si制备6.5%Si高硅钢过程组织结构与性能演化研究

基于物理气相沉积(PVD)之直流磁控溅射镀膜技术在低硅钢薄板双面共沉积富Si膜,然后高温真空扩散处理使Si渗入低硅钢基体,提高基体含Si量。以沉积Fe5Si3膜+1 180℃×1h扩散为1回合增Si处理,研究了多回合循环增Si处理过程硅钢基体组织结构与性能的演化机理。采用光学显微镜对样品进行了金相分析,采用扫描电镜(SEM)观察了样品的微观组织形貌,并用能谱分析仪(EDS)进行成分分析。用X射线衍射仪(XRD)和透射电镜(TEM)表征了样品的结构特征。经过4回合循环增Si处理可将0.35mm厚低硅钢基体含Si量由3%提高到6.5%,且沿厚度方向Si浓度分布均匀。相比于初始态低硅钢基片,PVD法制成6.5%Si高硅钢中高频铁损值降低40%~50%。     

Effect of cooling rates on the microstructure of proeutectoid ferrite in Fe-0.76%C alloy under high magnetic field

研究了在12 T强磁场下冷却速率对Fe-0.76%C钢中先共析铁素体的显微组织和性能的影响,结果表明: 先共析铁素体晶粒的伸长方向与磁场方向的夹角随着冷速度的提高而增大,其原因是高速冷却时原子扩散减弱. 在冷却速率相同的条件下, 与非磁场热处理样品相比,强磁场热处理样品的先共析铁素体面积明显增加, 宏观硬度下降,因为强磁场使Fe-0.76%C钢表现出更明显的亚共析钢特征.     

Effect of Cr and Mn on the microstructure of spray-formed Al-25Si-5Fe-3Cu alloy

The hypereutectic Al-Si-Fe alloys with different Mn and Cr addition were synthesized by spray forming technique, and the microstructural evolutions induced by Mn and Cr have been investigated using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results show that the modification effect of co-addition of Mn and Cr is more effective than the individual Mn or Cr addition in transforming harmful rod-like Fe-bearing β phase to particulate α-phase. Meanwhile, the modification effect of Cr is superior to that induced by Mn. The Mn/Cr ratio plays an important role in the combined addition. The addition of 2 wt% Mn + 1 wt% Cr to spray formed alloy has induced an ideal microstructure with entirely fine granular intermetallic compounds dispersed in Al matrix. DSC analyses indicate that both Mn and Cr can greatly influence the onset temperatures and the region widths of primary Si, δ phase and α phase, but bring little changes on multi-phase reaction, which would contribute to the modification effects of Mn, Cr and Mn + Cr.     

电爆喷涂技术在材料表面制备涂层的研究进展

综述了电爆喷涂技术在材料表面制备涂层的研究进展和应用.给出了电爆喷涂技术的特点,喷涂设备的工作原理以及喷涂材料的种类;详细讨论了放电参数、喷涂材料与基体材料的几何尺寸、喷涂室气压、复合涂层等因素对涂层质量的影响;列举了电爆喷涂技术的实际应用;进一步分析了将来需要研究的问题.