便携式X射线荧光光谱仪检测贫铀棒材表面镍锌镀层厚度

为了确保贫铀棒材表面防腐性能满足使用要求,需要准确地测量产品表面的镍镀层和锌镀层厚度。采用便携式X射线荧光光谱仪(PXRF)对贫铀棒材表面双镀层的各层厚度进行检测,实现了对镍镀层和锌镀层厚度非破坏性的测量。选用特征谱线强度分布均匀的镀层样品和未镀镀层的贫铀基体样品,采用PXRF检测,结果表明,基体射线对检测谱线无干扰。分别选取相同厚度镍镀层、不同厚度锌镀层的样品,相同厚度锌镀层、不同厚度镍镀层的样品,以及镍镀层、锌镀层厚度均不相同的样品,采用PXRF进行检测,结果表明,实验方法可识别相同基体上不同厚度的镍镀层和锌镀层,可实现镍锌组合镀层中两种镀层厚度的同时测量。根据贫铀棒材样品结构特点和镍镀层和锌镀层厚度的技术要求,设计制作了对比试样,分别绘制贫铀棒材样品镍镀层和锌镀层厚度与其对应特征峰强度的校准曲线,结果表明,校准曲线线性相关系数r均不小于0.999 4。采用实验方法检测贫铀棒材样品表面镍镀层和锌镀层厚度,同时在任意圆周上均匀地取6个检测点,采用金相显微镜法进行检测求得平均值,结果表明,实验方法测定结果相对标准偏差(n=6)不大于5.1%;与金相显微镜法基本一致,两种方法差值为-1.57~1.70 μm。     

WC复合镀层耐腐蚀性能研究

采用复合电沉积工艺制备了Ni-WC复合镀层,通过SEM、EDS和金相显微镜对其表面和断面形貌进行了观察,并借助电化学手段研究了Ni-WC复合镀层在3.5%NaCl腐蚀液中耐蚀性能。结果表明:WC微粒随着电沉积过程逐步埋入复合镀层并均匀分布,镀层与基体间结合良好,在3.5%NaCl腐蚀液中,复合镀层比纯镍镀层相比,腐蚀电位正移而腐蚀电流减少,耐腐蚀能力得到提高。     

稀土在化学沉积中的应用

通过金相显微镜观察了镀液中含不同浓度氯化铈( CeCl3)时所得镍镀层的表面形貌,考察了CeCl3对镍镀层显微硬度和耐蚀性的影响.结果表明,适量的CeCl3可提高Ni-P镀层的沉积速度,改善镀层的表面质量,提高镀层的显微硬度和增加镀层的抗腐蚀能力.     

使用温度对镀铝锌合金镀层微观结构的影响

采用金相显微镜和电镜研究了铝锌合金镀层钢板在不同温度条件下使用的镀层微观结构.结果表明:在300～450℃的温度范围内长时间使用,镀层表面颜色虽没有变化,但随温度的提高枝晶裂纹逐渐扩展,扩散生成的Al-Si-Fe合金层逐渐由断续分布到连续分布,厚度增加,以致镀层与钢板基体开裂、剥落,耐蚀性能降低.500℃时,镀层很快全部合金化和氧化变色,镀层鼓泡,完全丧失耐蚀性能.     

热镀锌合金化层铁含量对X射线荧光光谱法 测定镀层质量影响的探讨

采用X射线荧光光谱法(XRF)测定热镀锌合金化镀层时,由于ZnKβ或FeKα特征谱线强度随着合金化层中Fe含量的变化而变化,导致镀层分析结果产生偏差。实验分别用X射线荧光光谱法和重量法进行合金化热镀锌样板的镀层质量检测,验证不同Fe含量变化对X射线荧光光谱法分析镀层质量的影响程度;建立了两种检验方法的差值与Fe含量的回归关系,利用w=(w_Fe-10.81)/0.9960+w＇(其中w为校正后镀层质量;w_Fe为铁含量,%;w＇为校正前X射线荧光光谱法测定的镀层质量)对X射线荧光光谱法测量镀层质量偏差的校正。研究表明:Fe质量分数控制在8%~12%范围内,采用X射线荧光光谱法测量合金化镀层质量能满足精度控制要求,可以接受;w(Fe)＜8%或w(Fe)＞12%时,利用回归方程式理论校正由于Fe含量变化引起的X射线荧光光谱法测量合金化镀层的偏差,提高了分析准确度。对不同Fe含量合金化热镀锌钢板镀层质量的验证结果表明,校正后镀层质量的测定值与重量法测定值一致。     

锌镍合金镀层厚度的研究

用Q235钢研究了锌镍合金中镍含量对热浸镀锌层厚度的影响。试验结果表明:当锌浴中w(Ni)<0.12％时,镀层厚度随镍含量增加而减薄;当w(Ni)>0.12％时,镀层厚度有随镍含量增加而增加的趋势。由于锌浴中加入了镍,锌镍合金镀层明显地薄于纯锌镀层。随着浸镀时间的增长,锌镍合金镀层厚度是以某一抛物线趋势增加,纯锌镀层则呈直线增加。     

浸锌时间对热镀锌钢丝性能及组织的影响

利用扫描电镜、金相显微镜手段对相同原材料的钢丝在不同浸锌时间下的微观组织进行分析;研究了浸锌时间对热镀锌钢丝微观组织的影响;对不同浸锌时间的钢丝进行力学性能测试,并结合钢丝组织探讨了不同组织对钢丝性能的影响.研究结果表明:适当减小浸锌时间,可缩小镀层中脆性相的厚度;但过低的浸锌时间会导致镀层不均匀、合金层开裂等问题,从而降低钢丝的扭转性能.     

辉光放电发射光谱法测定钢板镀锌层中铅镉铬

通过条件试验,确定了辉光放电发射光谱仪(GD-OES)的最佳分析参数为:分析功率30 W、氩气气压620 Pa、预溅射时间200 s、积分时间10 s。选用多种基体标准样品,通过溅射率校正建立校准曲线,定量分析镀锌板镀层中铅、镉、铬元素含量及分布状况,得到镀锌层中各元素随深度变化的分析谱图,方法定义了镀层中元素积分计算方法,从而得到镀层中铅、镉、铬元素含量。以纯锌标准样品进行检出限测定,各元素的检出限分别为3.65(铅)、1.33(镉)、0.21(铬) μg/g;以纯锌标准样品进行短期精密度考察,3个元素测定结果的相对标准偏差(RSD, n=15)分别为2.8%(铅)、1.3%(镉)、6.6%(铬)。制备了典型涂镀样板,采用实验方法进行测定,并采用电感耦合等离子体质谱法进行比对分析,结果一致性较好。实验方法适用于快速定量测定钢表面1～50 μm厚度的镀锌板镀层中铅、镉、铬元素含量。     

X射线荧光光谱法测定锌铁合金镀层铁含量的影响因素探讨

采用理学Simultix14型X射线荧光光谱仪测定锌铁合金镀层铁含量时,发现有部分试样的检测结果与国家标准推荐的方法存在较大差异,经验证,该设备不适用于低镀层量的试样和高强钢试样。实验从X射线荧光光谱仪(XRF)的检测原理、锌铁合金板的平整度、合金层结构、试样表面镀层均匀性、表面粗糙度及表面后处理等方面探讨了影响X射线荧光光谱法测定锌铁合金镀层铁含量准确性的原因。结果发现,实验用X射线荧光光谱仪的检测原理决定了该设备只适用于镀层质量大于40g/m²的试样;试样不平整时,检测结果偏大;试样的合金层结构(钢种)、镀层均匀性及表面粗糙度也会影响检测结果的准确性;而试样表面后处理(L处理)对检测结果无影响。该设备适用于镀层质量较大的平整的软钢试样。     

用电化学阻抗谱研究钢表面三种电镀镍层的耐蚀性

在钢基体S 47220上分别电镀光亮、无光亮和多层镍镀层,采用电化学阻抗谱、极化曲线等研究在3.5%的Na Cl溶液中钢基体、纯镍和镀镍样品的腐蚀电化学行为,采用中性盐雾试验测试三种镀层的耐蚀性.结果表明,多层镍镀层比单一镍镀层表面更加致密,更难发生钢基体的优先腐蚀,因此保护性更好.钢基体、光亮镍镀层和无光镍镀层的等效电路模型分别是R_s(R_(ct)Q_(dl))(R_(pit)Q_(pit))、R_s(R_(ct)Q_(dl))(R_(pore)Q_(pore))和R_s(Q_(film)(R_(film)(R_(ct)Q_(dl)).在中性盐雾试验中,三层镍镀层经盐雾试验288 h后未发生腐蚀,因为其等效电路图Rs(RctQdl)与单质镍相同,具有相似的抗电化学腐蚀性能,所以耐蚀性优异,远高于单一镍镀层.     

不粘锅纳米涂层的剖面解析

不粘锅广泛应用于人们日常烹饪中,其耐用性和安全性与人体健康息息相关。不粘锅的使用性能主要取决于表面涂层质量,目前常规涂层测试手段并不能分析涂层的成分和构造,从而难以精确评价涂层的使用性能。实验用剖面金相、波谱和能谱成分分析等技术方法解析了不同厂家纳米锅的涂层。首先用波谱仪分析了涂层表面的成分,然后用剖面金相分析了涂层的构造,结果表明,不同品牌不粘锅的涂层均由外层有机物和内层无机物组成,其中外层有机物均为聚四氟乙烯,厚度约14~30μm,不同品牌锅的内层无机物成分和厚度差异很大,成分为类金刚石或纳米氧化铝颗粒和硅颗粒的混合物,厚度分布在12~100μm之间。不同涂层的差异直接导致涂层表现出不同的硬度和附着牢固性能。实验方法可以分析涂层的构造、缺陷状况、厚度等,进而评定涂层的质量状况,弥补现有标准中规定的实验方法的不足。     

金相磨抛工艺对碳化钨涂层组织评定的影响

碳化钨涂层内部为复合相组织,硬度高脆性大,金相制备易导致涂层内部出现裂纹、分层、拔出等缺陷。本文利用超音速火焰喷涂制备WC-10Co-4Cr涂层,采用不同的金相研磨和抛光工艺,分别评定WC-10Co-4Cr涂层的组织。结果表明:不同的金相研磨和抛光工艺对WC-10Co-4Cr涂层的孔隙率的评定结果有明显影响。随着磨抛压力的上升,涂层内部孔隙的尺寸明显增大,涂层原有孔隙周边被压裂、脱落,且脱落碳化钨颗粒进一步增强了对涂层表面的磨削效果,使得涂层表面的局部区域出现大范围脱落,从而导致随着研磨压力的上升,涂层的孔隙率升高了12.5%至30%,随着抛光压力的上升,涂层的孔隙率升高了近一倍。因此,为降低磨抛工艺对涂层组织评定的影响,建议使用15N的磨抛压力开展碳化钨涂层的金相制备,以获得更加准确的金相评定结果。     

Surface Modification With Zinc and Zn-Ni Alloy Compositionally Modulated Multilayer Coatings

Zinc and Zn-Ni alloy compositionally modulated multilayer （CMM） coatings were electrodeposited on to a steel substrate by the successive deposition of zinc and Zn-Ni alloy sublayers from dual baths. The coated samples were evaluated in terms of the surface appearance, surface and cross-sectional morphologies, as well as corrosion resistance. The microstructural characteristics that were examined using the field emission gun scanning electron microscopy （FEGSEM） confirmed the layered structure, grain refinement of the zinc and Zn-Ni alloy CMM coatings, and revealed the existence of microcracks caused by the internal stress in the thick Zn-Ni alloy sublayers. The corrosion resistance that was evaluated by means of the salt spray test shows that the zinc and Zn-Ni alloy CMM coatings were more corrosion-resistant than the monolithic coatings of zinc or Zn-Ni alloy of the same thickness. The possible reasons for the better protective performance of Zn-Ni/Zn CMM coatings were given on the basis of the analysis on the micrographic features of zinc and Zn-Ni alloy CMM eoatings after the corrosion test. A probable corrosion mechanism of zinc and Zn-Ni alloy CMM coatings was also proposed.     

料浆法制备NiCrW基高温合金Al-Si涂层的微观结构与性能

航空发动机涡轮叶片在使用时需加以涂层防护,以提高基体合金的抗高温氧化性能。本研究采用料浆渗铝的制备工艺,以CaCl₂作为活化剂,在NiCrW基高温合金表面制备Al-Si涂层。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)及能谱仪(EDS)对涂层试样的表面和截面进行分析。结果表明,聚乙烯醇水溶液可作为料浆法制备渗铝/铝硅涂层的有效黏结剂;高温扩散的温度和时间显著影响渗铝涂层的厚度。渗剂成分为5%Si+30%Al(质量分数),制备得到的共渗涂层由外而内依次为富Al层、NiAl层和含Si过渡层三部分,涂层致密无明显缺陷,厚度约为57μm。10%Si+25%Al、15%Si+20%Al与20%Si+15%Al共渗涂层由外而内分为富Al层、富Ni层和含Si过渡层三层。Si元素主要以含Si的沉积相形式存在于含Si过渡层中,少量沉积于外层。而Si的少量添加能明显影响Al、Ni元素的扩散过程,从而减小涂层厚度,并由单一NiAl相向富Al、富Ni的镍铝相转变。     

Tribological properties of FeCoCrNiAlBx high-entropy alloys coating prepared by laser cladding

FeCoCrNiAlBx(x=0, 0.25, 0.50, 0.75) coatings were prepared by laser cladding to study the effects of boron on the structure and properties of high-entropy alloys coatings.The microstructure, microhardness, and wear resistance properties of the samples were investigated by scanning electron microscopy, X-ray diffraction, metallographic micro-hardness test, and friction-wear test, respec-tively, and the mechanism of the wear behavior was also analyzed.The results showed that the high-entropy alloys consisted of BCC phase and eutectic structure, which contained FCC phase and M2 B. With boron addition, the content of BCC phase increased while that of eutectic structure decreased. The wear resistance of the high-entropy coatings was considerably improved with increasing addition of boron, and accordingly, the FeCoCrNiAlB0.75 coating showed the best wear resistance.     

炭/炭复合材料磷酸盐涂层的抗氧化性能

采用浸渍技术制备多种炭/炭复合材料磷酸盐抗氧化涂层.在700℃下测试涂层的抗氧化性能,结果表明:浸渍混合成分磷酸盐涂层的炭/炭复合材料的抗氧化性能明显高于浸渍单一成分磷酸盐涂层试样,其最佳抗氧化效果为20 h氧化的质量耗损率仅为0.98％.采用SEM观察相关试样氧化实验前后的表面形貌,发现单一磷酸锌或者磷酸锰的涂层在氧化时挥发严重,单一磷酸铝的涂层则发生团聚:混合组分的涂层成分的挥发则得到有效抑制,无团聚现象,并提出了混合磷酸盐的复合抗氧化机制.     

便携式X射线荧光光谱仪分析镀锌板铬盐钝化膜涂镀量

镀锌板铬盐钝化膜涂镀量是生产工艺控制和膜厚度质量控制的一个重要指标,为提高现场质量控制效率、降低质量控制成本,急需一种无需复杂样品前处理、实现涂镀量实时在线分析的方法。实验采用圆片取样机制样法制取标样,建立了用便携式X射线荧光光谱(PXRF)对镀锌板铬盐钝化膜涂镀量进行实时、在线定量分析的方法。铬盐钝化膜涂镀量与Cr元素含量存在对应关系,实验通过分析Cr元素来表征钝化膜涂镀量。为获得镀锌板铬盐钝化膜体系中Cr元素的最佳激发效果,比较了5种不同分析条件,并确定采用电压15kV、电流10μA作为实验的分析条件;研究了元素谱线之间的干扰重叠校正以及基材元素对待测元素的干扰,采用α经验系数法进行基体校正,避免基体元素Zn和Fe两种元素对Cr元素分析准确度的影响;讨论了检出限的计算方法,采用涂镀量低的样品作为测试样,根据多次测试结果的标准偏差来计算检出限,铬盐钝化膜涂镀量的检出限值为0.92mg/m²;对方法的精密度进行考察,相对标准偏差(RSD)控制在1.5%之内;经与电感耦合等离子体原子发射光谱法(ICP-AES)进行比对,相对误差控制在2.5%之内,方法的准确度能够满足现场质量控制要求,实现了样品的实时、在线分析,提高了测试效率。     

Scanning auger microprobe study of hot-dipped regular-spangle galvanized steel: Part I. surface composition of As-produced sheet

Untreated bright and dull zinc coatings produced on a hot-dipped-coating pilot line from a zinc bath containing small concentrations of aluminum, antimony, and lead were examined with a scanning Auger microprobe. The results show that the entire surface of the zinc coating was covered by a very thin, continuous film comprised of aluminum and oxygen. The thickness of this film, of the order of 5 nanometers, was the same for both bright and dull coatings and independent of zinc spangle roughness. Beneath this film the zinc surface contained numerous small precipitates that occupied a considerable portion of the total coating surface area, perhaps as much as 25 pct for some spangles. In all, five distinct types of precipitates were observed in the coatings. Aluminum was common to each type except for one which was essentially pure lead. In the others the principal element combined with aluminum was oxygen in one case, antimony in the second, iron in the third, and zinc in the fourth case. Based on the results of Auger electron spectrometry, these appear to be A1₂O₃, AlSb, one of the aluminum-rich iron-aluminum intermetallic compounds, and the zinc-rich solid solution of zinc in aluminum, respectively. The size of these various precipitate particles tended to be larger and their frequency greater in rough than in smooth spangles.     

Scanning auger microprobe study of hot-dipped regular-spangle galvanized steel: Part II. surface composition of chromated sheet

Zinc coatings produced on a hot-dipped-coating pilot line from a zinc bath containing small amounts of aluminum, antimony, and lead were treated with a commercial chromating solution and then examined with a scanning Auger microprobe. The results show that the chromating solution attacked the thin aluminum oxide precipitates in the zinc surface. The invisible conversion-coating film that was formed on the zinc matrix consisted mainly of oxygen, zinc, and chromium in order of decreasing atomic concentration. Surprisingly, the thickness and composition of the film was the same for treatment in 8 and 15 grams-per-liter chromate solutions. The film that was formed on precipitates of lead in the surface of the zinc coating was much thicker and richer in chromium than the film formed on the surrounding zinc. Examination of chromated surfaces exposed to water-saturated air at 100 °F and to normal atmospheres showed that the surfaces corroded rapidly on a microscale. After only a few hours exposure the surface had numerous mounds composed of equal atom concentrations of zinc and oxygen. In each instance corrosion sites were associated with a lead precipitate.