激光熔覆Fe基非晶／纳米晶复合涂层的组织与性能

对以激光熔覆方式在45钢基体上制备的FeNiSiBVRE非晶涂层进行激光晶化,制备非晶／纳米晶复合涂层.利用X射线衍射仪、透射电镜、扫描电镜和磨损试验机研究非晶／纳米晶复合涂层的组织与性能.研究结果表明,涂层存在着分层结构,组成相有晶化相、非晶相和纳米晶相;涂层底部和顶部的显微组织由大量的稀土树枝晶、板条状硼化物和粒状碳化物组成,涂层中部的显微组织是由大量的纳米晶相镶嵌在非晶基体上构成.与没有进行激光晶化的非晶涂层相比,涂层的耐磨损性能下降.其磨损机制以粘着磨损和剥层磨损为主.     

激光熔覆Fe基非晶／纳米晶复合涂层的组织与性能

对以激光熔覆方式在45钢基体上制备的FeNiSiBVRE非晶涂层进行激光晶化,制备非晶／纳米晶复合涂层,利用X射线衍射仪、透射电镜、扫描电镜和磨损试验机研究非晶／纳米晶复合涂层的组织与性能,研究结果表明,涂层存在着分层结构,组成相有晶化相、非晶相和纳米晶相;涂层底部和顶部的显微组织由大量的稀土树枝晶、板条状硼化物和粒状碳化物组成,涂层中部的显微组织是由大量的纳米晶相镶嵌在非晶基体上构成,与没有进行激光晶化的非晶涂层相比,涂层的耐磨损性能下降,其磨损机制以粘着磨损和剥层磨损为主。     

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.     

Ni-ZrO_2纳米复合涂层的制备及其耐磨耐蚀性能研究

采用电火花沉积和激光熔覆技术在45号钢基体表面沉积制备Ni-ZrO2复合涂层。通过研究涂层的显微硬度分布、耐磨和防腐性能发现:在900 W功率下,电火花沉积的Ni基过渡层质量较好,过渡层厚度达到了110μm左右,且与基体冶金结合具有较高的结合力。利用激光熔覆技术在Ni基过渡层上熔覆纳米ZrO2粉体(3Y-TZP),纳米ZrO2涂层平均厚度约为20μm。Ni-ZrO2纳米复合涂层的表面平均硬度为934.19HV0.1,最高硬度可达1 145HV0.1,相对于基体,硬度提高了3.8倍。摩擦磨损和腐蚀试验发现复合涂层的耐磨性能和耐蚀性能较基体都有明显的提升。     

激光熔覆钛基复合涂层的显微组织和硬度分析

采用激光熔覆快速非平衡合成方法制备了原位反应合成TiB增强钛基复合材料.用Y2O3、Ti和B的混合粉末在Ti-6Al-4V基体表面激光熔覆制得TiB/Ti复合涂层.采用X线衍射仪(XRD)、扫描电子显微镜(SEM)、能量散射光谱仪(EDS)和硬度测试等方法,研究了原位合成TiB/Ti复合涂层的显微结构和显微硬度.结果显示:激光熔覆层的相结构主要为α-Ti和TiB两相,TiB增强相均匀地分布于复合涂层中,熔覆层的硬度值高于基体Ti合金的硬度值1倍以上,Y2O3含量(质量分数w,全文同)为1％的激光熔覆涂层内部的增强相组织最为均匀、细小,且硬度值也最高,平均硬度(HV)值约为830.     

Fe41Co7Cr15Mo14C15B6Y2合金涂层的激光制备及显微组织研究

利用激光熔覆和激光重熔的方法在低碳钢表面制备了原位生成颗粒增强铁基涂层.用X线衍射(XRD)、扫描电镜(SEM)对其相结构和微观组织进行了研究,重点分析了重熔层的组织形态和形成机制.结果表明:制备的涂层无气孔和裂纹,整个涂层的厚度为0.6~0.7 mm,重熔层厚度为50~80 μm;熔覆层主要是方向比较紊乱的树枝晶组织,重熔层内形成了细小的等轴晶组织;重熔层最高显微硬度达到了1056 HV.     

镁合金表面APS法制备ZrB_2-ZrC基复合涂层

针对镁合金抗烧蚀性差的问题,采用高能等离子喷涂在AZ91镁合金表面引入NiCoCrAlTaY过渡层后制备复合结构陶瓷涂层.复合陶瓷抗烧蚀层结构设计为小颗粒的SiC和ZrO_2填充于大粒径的ZrB_2和ZrC颗粒周围的四组元复合结构.采用球磨机械混合的方法将平均粒径为10μm的ZrB_2和ZrC粉末及平均粒径为1μm的SiC和ZrO_2粉末混合均匀,形成1μm小颗粒的SiC和ZrO_2均匀填充于10μm粒径的ZrB_2和ZrC颗粒的混合结构粉末作为喷涂粉末,通过大气等离子喷涂方法在46.5kW功率条件下制备复合结构陶瓷涂层.研究结果表明:复合陶瓷层内部组织为小尺寸的SiC和ZrO_2填充于大粒径的ZrB2和ZrC颗粒的四组元复合结构,达到四元复合结构的设计,涂层内部颗粒发生明显的扁平化,涂层显微硬度达到1 311kgf·mm~(-2).通过X射线衍射分析发现在涂层制备过程中粉末没有发生明显的相结构改变,透射电子显微镜微区分析表明在ZrB_2和ZrC大颗粒交界处出现B_2O_5Si非晶环带玻璃相的亚稳结构,有利于抗烧蚀性的提高.     

热喷涂制备铝基复合材料涂层及其热处理工艺

为了提高铝基涂层的硬度和耐磨性,研制了两种新型复合材料涂层.采用可控气氛等离子喷涂的方法制备了不同比例的铝-氧化铝、铝-铝青铜复合材料,通过扫描电子显微镜观察复合材料的组织形貌并进行成分分析,测定了其显微硬度.再对制得的复合材料涂层进行再结晶热处理,再次进行组织形貌观察和相分析,并进行显微硬度测试.结果表明：当铝和氧化铝比例为4∶3,铝和铝青铜比例为1∶3,热处理温度在350℃时,所得到的复合材料涂层的组织分布均匀,晶粒细小.     

超音速火焰喷涂两种WC-17%Co涂层的组织和性能研究

采用超音速火焰喷涂法制备纳米和普通WC-17%Co涂层,借助于SN-3400型扫描电镜(SEM)、D8型X射线衍射仪(XRD)、HXD-1000TM型显微硬度计、SHT4605型拉伸试验机和TRB型球盘磨损试验机对涂层组织结构、相组成、显微硬度、结合强度及耐磨性能进行了分析.结果表明,两种WC-17%Co涂层形成过程中WC发生了分解,并形成了W2C、W和CoxWyCz(Co3W3C、Co3W9C4)等一些新相,纳米涂层的组织形态明显好于普通涂层,组织晶粒细小,WC晶粒保持在120~150 nm的纳米尺度范围;纳米涂层的显微硬度、结合强度和耐磨性都高于普通涂层,相比之下,纳米涂层的显微硬度、结合强度比普通涂层高出近30%,在相同的试验条件下普通涂层的磨损体积是纳米涂层的2倍.     

AZ91D镁合金表面复合涂层的微观形貌与性能

为了提高AZ91D镁合金的耐腐蚀性和耐磨性,用硅酸盐体系溶液和以乙酸镍为主盐的镀液在AZ91D镁合金表面制备了等离子体电解氧化和化学镀镍复合涂层.SEM分析结果表明,复合涂层表面呈典型的胞状结构,复合涂层中的镀镍层自氧化膜的紧密层和疏松层的交界处向外生长,镀镍层和氧化膜之间呈"机械咬合"式结合.XRD分析结果表明,复合涂层外层和内层的相组成主要为非晶态Ni-P合金和Mg2SiO4、MgAl2O4等.与AZ91D镁合金相比,复合涂层的显微硬度为基体的6倍;自腐蚀电位提高了约1.2 V,自腐蚀电流密度降低了2个数量级.制备复合涂层之后,AZ91D镁合金的性能得到显著的改善.     

Enhanced Corrosion and Wear Resistances of Zr-based Alloy Induced by Amorphous/Nanocrystalline Coating

To improve corrosion and wear resistances of the Zirconium(Zr) based alloys which are widely applied in nuclear reactors and chemical corrosion-resistant equipment, a new surface modification scheme was designed to deposit a Zr_(75)Cu_(25) coating on Zr substrate by using magnetron sputtering technique. The microstructure and the phase composition were characterized by scanning electron microscope, transmission electron microscope, and X-ray diffraction measurements. The tribological properties and the corrosion resistance were investigated by performing reciprocating tribo-tester and electrochemical tests, respectively.It is found that the Zr_(75)Cu_(25) coating is made up of a mixture of amorphous and a-(Zr) nanocrystalline phases.The nanocrystalline particles with a size of 5-10 nm are homogenously dispersed in the amorphous matrix.The Zr_(75)Cu_(25) coating shows excellent tribological properties, due to the dispersion strengthen caused by the homogeneous distribution of a-(Zr) nano-size particles among the amorphous matrix. In addition, it is revealed that the Zr_(75)Cu_(25) coating makes the Zr substrate exhibit excellent corrosion resistance, due to the robust passive film with a compact structure of the amorphous/nanocrystalline mixture.     

Effects of heat-treatment on crystallization and wear property of plasma sprayed Fe-based amorphous coatings

The Fe-based amorphous coatings were produced by air plasma spraying. The as-sprayed coatings were heat-treated at the temperature of 573, 873, and 1 023 K, respectively. The crystallization and wear behavior of the heat-treated amorphous coatings were investigated. It was found that the amorphous-nanocrystalline transformation appeared when the as-sprayed coatings were treated at 853 K. The crystallization process had completed and a coating with microcrystallines was formed when the treatment temperature reached 1 023 K. The resultant amorphous and nanocrystalline composite coatings exhibited superior wear resistance compared to crystalline coating. It is attributed to fine grain strengthening of formed nanocrystallines.     

碳纤维增强氧化锆热障烧蚀复合厚涂层的研究

采用大气等离子喷涂(APS)技术,在TC4基体上制备出一种类似"钢筋混凝土"结构碳纤维增强的氧化锆热障烧蚀复合厚涂层,并用等离子火炬对涂层进行模拟烧蚀隔热试验,采用扫描电镜(SEM)、X射线能谱分析(EDS)等测试方法对涂层烧蚀前后的表面形貌、纤维状态进行了观察,对部分结构、成分进行了确定。研究结果表明,经过纤维增强的复合涂层可制得的厚度要远大于传统的复合涂层,其烧蚀隔热作用也较传统热障涂层有明显提高。     

ON ZrO_2-NiCr COMPOSITE POWDER FOR SPRAYING

Composite powder prepared of calcium ox-ide stabilzed ZrO_2 (CSZ)and NiCr by vacuum sintering isstudied, and the effect of additive TiO_2,on its properties isdiscussed. The morphology and phases of the powder weremeasured and determined by SEM.EPMA. XRD methodsand the testing of flowability, bulk density and microhard-ness. The results show that the metallic camponents in thepowder are in homogeneous distribution,the flowability.bulkdensity and microhardness are superior to the ZrO_2-NiCrpowder prepared by mechanically mixing. All components inthe coating made of the composite powder are well-distribut-ed because of avoiding segregation in the middle of mixing.It proves that the comopsite powder is an excellent materialfor plasma spraying.     

反应热喷涂法制备陶瓷涂层的研究

首先通过差热-失重分析和XRD测试手段对反应热喷涂Al＋TiO2＋H3BO3混合粉体以制备Al2O3/TiB2复合陶瓷涂层的可行性进行了分析.然后对喷涂后试样涂层的耐磨性进行了研究.结果表明：Al＋TiO2＋H3BO3混合粉体差热-失重分析和在1200℃烧结后XRD测试分析均表明完全可以反应生成所需的Al2O3/TiB2复合陶瓷涂层.所制备陶瓷涂层的耐磨性要比基体提高1倍左右.     

Effect of laser remelting on the microstructure and corrosion resistance of plasma sprayed Fe-based coating

Fe-based amorphous and nanocrystalline coatings were fabricated by air plasma spraying. The coatings were further treated by laser remelting process to improve their microstructure and properties. The corrosion resistance of the as-sprayed and laser-remelted coatings in 3.5wt% NaCl and 1 mol/L HCl solutions was evaluated by electrochemical polarization analysis. It was found that laser-remelted coating appeared much denser than the as-sprayed coating. However, laser-remelted coating contains much more nanocrystalline grains than the as-sprayed coatings, resulting from the lower cooling rate in laser remelting process compared with plasma spraying process. Electrochemical polarization results indicated that the laser-remelted coating has great corrosion resistance than the as-sprayed coating because of its dense structure.     

非晶/纳米晶磁粉芯的热压制备工艺探究

在不使用粘接剂的条件下,通过Gleeble-3500热模拟试验机将Fe-Si-B-Cu-Nb非晶合金粉末在其过冷液相区直接热压成型,制备成非晶/纳米晶磁粉芯。研究热压压力和热压时间对非晶/纳米磁粉芯密度的影响,并与传统冷压或温压成型条件下获得的非晶/纳米晶磁粉芯的性能进行比较。结果表明,在180 MPa,快速升温到723 K,再缓慢升温到773 K,保温1 h,最后空冷的热压工艺条件下,制备的磁粉芯样品中形成了纳米微晶镶嵌于非晶体的非晶/纳米晶双相结构。与传统冷压或温压条件下制备的磁粉芯相比,制备的磁粉芯具有更高的密度,约为6.8g/cm3;较高的饱和磁感应强度,约为1.34T;较低的矫顽力,约为2A/m。     

热喷涂HA复合涂层的组织分析

为了制备羟基磷灰石（HA）复合涂层,采用化学沉淀法制备羟基磷灰石粉末,对制备的超细粉末加入PVA溶液充分搅拌、干燥、研磨和过筛,制备出微米级、近似球状的、在等离子送粉器中容易流动的羟基磷灰石粉末.利用等离子喷涂和电弧喷涂的复合喷涂方法制备出羟基磷灰石不锈钢复合涂层和氧化铝不锈钢复合涂层,并通过扫描电镜分析了涂层的组织形态.结果表明,羟基磷灰石粉末比重很轻,不易进入等离子弧中心而被融化,等离子弧将羟基磷灰石粉末加热并载入电弧喷涂气流中,由不锈钢雾化液滴一并打在基体上形成复合涂层.对于氧化铝/不锈钢涂层和复合涂层,2种粒子虽然分布不均匀,但却获得了良好的冶金结合.     

激光重熔制备TA1表面Ni/Al复合抗高温氧化涂层

为了提高纯钛的高温抗氧化性能,采用电弧喷涂和等离子喷涂方法在纯钛表面制备Ni/Al复合涂层.利用激光重熔使得Ni层与Al层发生冶金反应,对试件进行800℃×40 h连续氧化.根据生成的金属间化合物特征研究纯钛的高温抗氧化行为.结果表明,经过表面改性处理后Ni/Al复合涂层可以显著提高纯钛的高温抗氧化性能.在激光重熔过程中Ni/Al复合涂层中的Al发生熔化扩散并与Ni形成以Ni_2Al_3相为主的扩散层.在氧化过程中Ni/Al复合涂层表面形成连续且致密的α-Al_2O_3氧化膜与大量NiAl相,表面扩散层中的富铝相可为表面提供充足的Al元素,进而对纯钛基体提供有效的高温抗氧化保护作用.