Q235钢表面等离子熔覆碳化钨增强铁基合金层的组织和硬度

采用等离子弧熔覆技术在Q235钢基体上制备了镍包碳化钨增强(质量分数为50%)的铁基合金层;采用SEM、EDS和XRD等研究了合金层的组织,利用显微硬度计测试了合金层的显微硬度分布。结果表明:Q235钢表面合金层厚度可达2.6 mm,合金层中无裂纹、气孔等缺陷;合金层中WC颗粒部分溶解于铁基合金中,WC与合金层界面形成厚达数微米的反应层,其组织主要以γ-Fe为基体,其上分布着Cr_(23)C_6、Fe_3W_3C、WC和Ni_3B等强化相;合金层的显微硬度可达700～1 100 HV。     

高抗裂耐磨堆焊焊条的研制

为开发高抗裂高耐磨的堆焊焊条,采用H08A焊芯,通过调整药皮中的组分,设计了4种碱性焊条,然后分别在Q235钢基体上进行堆焊,采用光谱仪、硬度计、光学显微镜、扫描电镜和能谱仪等对堆焊层的化学成分、硬度和显微组织进行了分析,并研究了堆焊层的耐磨性和抗裂性。结果表明:优化成分焊条的堆焊层组织为混合型马氏体+少量残余奥氏体+弥散分布的一次NbC-TiC颗粒,低碳马氏体和高碳马氏体数量相当,硬度为58.1 HRC;堆焊层具有高的抗裂性能,连续堆焊不产生宏观裂纹;堆焊层的耐磨性也较好,约为淬火态45钢的1.41倍。     

TiC颗粒对铁-碳-铬-硅合金堆焊层显微组织及耐磨性的影响

用埋弧焊制备铁-碳-铬-硅合金堆焊层,通过显微组织观察、硬度测试和耐磨性能试验等方法研究了外加TiC颗粒含量对其显微组织及耐磨性的影响。结果表明:不同TiC含量的铁-碳-铬-硅合金堆焊层基体组织均为α-Fe,随TiC含量增加,初生M7C3颗粒尺寸从40~80μm逐渐减小至15~25μm,颗粒数量增多,分布弥散,且出现了TiC2和TiC等增强相;弥散密集分布的M7C3颗粒有利于堆焊合金层表面均匀磨损,避免因粗大脆性共晶优先磨损引起的过早失效,显著改善了耐磨性;该合金堆焊层的耐磨性随TiC含量的增加先增强,接着减弱,然后再增强,其主要磨损机理由微观断裂转变为微切削。     

激光重熔扫描速度对Co基合金堆焊层组织及耐磨性的影响

采用表面堆焊方法在Q345钢基体上堆焊Co基合金层，对其进行表面激光重熔。研究两种不同激光重熔扫描速度对堆焊层组织及耐磨性的影响。结果表明，堆焊层经表面激光重熔后组织明显细化，随着激光扫描速度的提高，重熔堆焊层组织不仅更加细化、均匀致密，而且硬度更高、耐磨性更好。     

等离子堆焊涂层成分优化及耐磨性能研究

为了提高材料表面的耐磨性,在Ni60基体合金粉末中加入了铬、锰、钨粉末,配置了一种新的合金粉末,并在Q235钢板上进行了等离子堆焊试验。以铬、锰、钨粉末的含量为因子,以硬度为指标,采用三水平三因子正交表进行统计分析,得到了较优粉末配方为：60（Cr）=10％,ω（Mn）=4％,ω（W）=7％,余为Ni60基体合金粉末。磨损试验结果表明：Q235钢板表面的耐磨性得到了提高,且随堆焊层硬度的增加,其耐磨性增强。     

焊后加热对Fe-Cr-C耐磨层组织硬度的影响

采用埋弧堆焊方法在Q235低碳钢基体上制备了Fe-Cr-C耐磨堆焊层.研究了焊后高温加热过程对Fe-Cr-C耐磨堆焊合金组织及硬度的影响,并探讨了焊后加热温度对碳迁移的影响.利用XRD、光学金相显微镜、SEM分析了焊层的显微组织.结果表明,高温加热后焊层的显微组织和物相发生了变化,堆焊层硬度降低,熔合线附近出现明显的增碳和脱碳层,分析了堆焊层组织硬度变化与加热温度的关系.     

等离子喷焊合金层组织及性能试验研究

对16Ｍn钢表面等离子喷焊的自熔性铁基合金喷焊层（Fe55）和镍基合金喷焊层（Ni60)进行了硬度、显微组织、X射线衍射分析及不同腐蚀介质下的耐磨性试验，结果表明，Fe55和Ni60合金喷焊层的显微组织均为γ固溶体基体上分布着多种复杂的化合物相，如Fe23(C,B)6、（Cr,Fe)7C3、Cr7C3、NiB等。在中性水中Fe55合金喷焊层的耐磨性优于Ni60合金，在酸碱腐蚀介质中则正好相反，但两种合金喷层耐磨性都有所降低，在酸性介质中降低更明显。     

氩弧熔覆TiCrCuFeNi高熵合金涂层的组织与性能

采用氩弧熔覆工艺在Q235钢基体上制备了TiCrCuFeNi高熵合金涂层,采用SEM、EDS、XRD等对该涂层的组织进行了分析,并对其硬度、耐磨性、耐蚀性进行研究。结果表明:高熵合金涂层主要由FCC固溶体、BCC固溶体及Laves相组成;涂层表面显微硬度可达754.5HV;涂层的耐磨性较好,优于熔覆钴基合金涂层的,干磨时主要磨损机理为磨粒磨损和粘着磨损;涂层在3.5%NaCl溶液中的耐蚀性比06Cr19Ni10不锈钢的优异。     

模具修复梯度耐磨堆焊层组织性能研究

提出了采用“母材 过渡层 耐磨层”的复合堆焊修复方法。工艺试验表明,通过打底焊过渡层的方法可以有效防止堆焊出现的裂纹。金相显微分析表明,采用Cr-Mo-W-Nb系耐磨堆焊焊条的堆焊合金组织为马氏体基体 残余奥氏体 碳化物,基体上分布的碳化物使堆焊层具有强的耐磨性。性能测试结果表明,堆焊表面平均硬度达到HRC60.1,完全满足模具材料硬度要求,硬度梯度分布合适,堆焊层耐磨性为母材的7.58倍。     

基于钴基合金覆层的多层金属热锻模原型制备与性能

基于功能梯度材料(FGM)的思想制备多层金属热锻模是提高模具寿命的有效方法。采用焊条电弧堆焊制备了多层金属热锻模的原型试样,试样经焊后热处理后,进行了金相组织分析、显微硬度测试、磨损实验和冲击韧性测试等实验。实验结果表明:钴基合金堆焊层与W6Mo5Cr4V2堆焊层界面冶金结合情况良好;截面显微硬度呈梯度分布,表面钴基合金硬度达到492HV;制备的多层金属试样耐磨性是H13钢耐磨性的2.5倍,冲击韧性处于合理范围。     

WC颗粒增强镍基合金喷熔层腐蚀磨损行为及其人工神经网络预测分析

采用氧一乙炔焰喷熔工艺制备了碳化钨（WC）颗粒增强镍基合金喷熔层,研究了它的腐蚀磨损行为。结果表明：喷熔层耐腐蚀磨损性能随WC含量增加而提高,WC含量在20％～30％范围内,喷熔层耐腐蚀磨损性能最佳,超过30％时,其耐腐蚀磨损性能下降。载荷增加,腐蚀磨损率增大;速度增加,腐蚀磨损率下降。低速重载荷时,WC颗粒增强效果明显,且含30％WC喷熔层耐腐蚀磨损性能最好;高速轻载荷时,因WC原电池效应显著,WC颗粒增强效果减弱。基于人工神经网络的喷熔层腐蚀磨损行为预测与实验结果吻合较好,对喷熔层的应用具有重要指导作用。     

感应熔敷微-纳米碳化钨复合涂层的耐磨性研究

用感应加热熔敷方法在Q235钢表面制备了微-纳米碳化钨复合涂层，并分析了涂层的微观结构、显微硬度及耐磨性。结果表明：涂层的组织主要由镍基固溶体和碳化钨颗粒组成。涂层与基体冶金结合；微-纳米碳化钨涂层的耐磨性比微米碳化钨涂层平均提高0．5倍。     

Microstructure and wear properties of in situ TiC/FeCrBSi composite coating prepared by gas tungsten arc welding

Using a gas tungsten arc welding (GTAW) process, in situ synthesis TiC particles reinforced Fe-based alloy composite coating has been produced by pre-coated FeCrBSi alloy, graphite and ferrotitanium powders on the substrate. The microstructure and wear properties of the composite coatings were studied by means of scanning electron microscopy (SEM), X-ray diffractometer (XRD) and wear test. The effects of thickness of the pre-coated powder layer on the microstructure, hardness and wear resistance of the composite coatings were also investigated. The results indicated that TiC particles were produced by direct metallurgical reaction between ferrotitanium and graphite during the GTAW process. TiC particles with sizes in the range of 3–5 μm were dispersed in the matrix. The volume fraction of TiC particles and microhardness gradually increased from the bottom to the top of the composite coatings. The TiC-reinforced composite coatings enhance the hardness and wear resistance. The highest wear resistance of the composite coating with a 1.2 mm layer was obtained.     

Microstructure and wear properties of in situ TiC/FeCrBSi composite coating prepared by gas tungsten arc welding

Using a gas tungsten arc welding (GTAW) process, in situ synthesis TiC particles reinforced Fe-based alloy composite coating has been produced by preplaced FeCrBSi alloy, graphite and ferrotitanium powders. The microstructure and wear properties of the composite coatings were studied by means of scanning electron microscopy (SEM), X-ray diffractometer (XRD) and wear test. The effects of thickness of the pre-placed powder layer on the microstructure, hardness and wear resistance of the composite coatings were also investigated. The results indicated that TiC particles were produced by direct metallurgical reaction between ferrotitanium and graphite during the GTAW process. TiC particles with sizes in the range of 3–5 μm were dispersed in the matrix. The volume fraction of TiC particles and microhardness gradually increased from the bottom to the top of the composite coatings. The TiC-reinforced composite coatings enhance the hardness and wear resistance. The highest wear resistance of the composite coating with a 1.2 mm layer was obtained.     

稀土镧对电火花沉积碳化钛陶瓷涂层耐磨性能影响

为研究稀土元素对电沉积TiC陶瓷涂层摩擦学性能的影响,采用自配TiC、Ni、Mo、WC混合粉末压制烧结电极,在45#钢基体上进行放电陶瓷沉积实验,并在HQ-1型摩擦磨损实验机上对不同稀土含量的陶瓷涂层进行了摩擦磨损实验。结果表明:电极中加入适量氧化镧对涂层摩擦学性能有改善作用,稀土氧化镧含量的最佳值为0.5%,此时磨损质量损失较未加稀土时减少了71.4%。当稀土加入量过多时,涂层耐磨性能反而降低,甚至低于不加稀土时的耐磨性能。通过对涂层表面扫描电镜分析(ASEM)和X射线衍射(XRD)分析可知,加适量稀土元素,可改善涂层表层组织结构,减少了表面气孔和开裂的现象发生。     

不同激光熔覆材料涂层的耐磨性能比较

本文研究了宽带激光熔覆不同熔覆材料的复合涂层的耐磨性能。结果表明:Ni60B熔覆层的硬度高于40Cr基材的硬度,Ni60B+WC梯度复合涂层具有最高的硬度,对于提高零件的抗磨损性能比较有利;Ni60B熔覆层和Ni60B+WC熔覆层均适合修复轴类零件;三层梯度复合涂层磨痕宽度最小,具有最好的耐磨性。     

Microstructure and Tribological Behavior of Laser in Situ Synthesized TiC-Reinforced Fe-Based Composite Coatings

Fe-based composite coatings reinforced with TiC particles were prepared by laser surface engineering from precursor of ferrotitanium and graphite. Microstructure of the composite coatings was comprised of dendritic TiC dispersed in a ferrite matrix. In situ dendritic TiC was formed by mechanism of precipitating from the liquid Fe–Ti–C alloy system. Composite coatings showed a substantial increase in microhardness in comparison to that of the substrate. Dry sliding wear tests performed at room temperature revealed that the in situ composite coating possessed a considerably reduced wear volume loss owing to the presence of in situ synthesized TiC. A relatively smooth surface was observed for in situ TiC/Fe composite coating due to its high resistance to ploughing and adhesion, which is caused by the uniformly dispersed TiC reinforcement with high volume fraction.     

等离子喷涂WC/Co Fe基涂层摩擦与磨损性能

以普通铸铁为基体,碳化钨陶瓷粉末WC 12Co为热喷涂材料,采用大气等离子法制备WC/Co Fe复合涂层.通过SEM、EDS、XRD等手段对WC/Co Fe涂层微观组织与结构进行表征,并对WC/Co Fe复合涂层耐磨损性能进行测试.结果表明,等离子喷涂制备的WC/Co Fe涂层物相以WC相为主;WC涂层摩擦因数波动小于铸铁材料摩擦因数,表明WC复合涂层具有良好的抗摩擦性能.WC涂层耐磨损性能高于铸铁,主要归因于WC颗粒韧性好、硬度高、抗冲击及抗磨损性能强,与基体金属的结合性好.     

镁合金表面再制造AlCoTi非晶涂层组织及力学性能研究

采用高速电弧喷涂技术在AZ91镁合金表面制备了高非晶含量AlCoTi涂层,研究了涂层显微组织、力学性能、摩擦磨损及电化学腐蚀性能。结果表明,涂层呈典型的层状结构,其结构紧凑,与镁合金基体结合良好,孔隙率约为1.63%。涂层的组织主要由非晶相、纳米结构的α-Al和Al3Ti相组成。相比于AZ91镁合金,AlCoTi非晶涂层具有更高的显微硬度和耐磨性能：涂层的显微硬度约为511.3Hv0.1,远高于AZ91镁合金(62Hv0.1);在相同的磨损条件下,非晶涂层相对耐磨性约为晶体结构AZ91镁合金的3.9倍,其主要磨损机制为脆性剥落。在0.6 mol/L NaCl溶液中,非晶涂层自腐蚀电位、自腐蚀电流密度和电荷转移电阻分别为-0.696V、0.741 8μA/cm²和33 660?·cm²,明显优于AZ91镁合金的-1.392V、769.3μA/cm²和1 914?·cm²。通过对镁合金表面不同防护涂层的电化学腐蚀性能和显微硬度比较分析,本研究为镁合金提供一种低成本、高性能的涂层材料及再制造关键技术。     

Role of Third Bodies in Friction and Wear of Cold-Sprayed Ti and Ti–TiC Composite Coatings

Titanium (Ti) and Ti-based alloy wear performance is often poor unless coating or lubricants are used. An alternative is to use hard phase reinforcement. Cold spray is a relatively new method to deposit composite coatings, where here we report the deposition of a Ti–TiC coating and its sliding wear behavior. Mixtures of mechanically blended Ti–TiC with various TiC content were injected into a de Laval nozzle and sprayed onto substrates. Two composite coatings and a pure Ti coating are reported here, where the as-sprayed compositions of the composites were 13.8 and 33.4 vol% TiC. Reciprocating dry sliding wear was performed using a custom-built in situ tribometer. All tests were conducted with a sliding speed of 3 mm/s and at a normal load of 0.5 N. Using a transparent sapphire hemisphere of 6.25 mm as counterface, dynamic behavior of third bodies was directly observed. It was found that adhesive transfer of Ti was the primary wear mechanism for the Ti coating, with oxidative and abrasive wear also occurring for longer sliding cycles. The superior wear resistance of the composite coatings compared to Ti was related to dual function of TiC particles, where they reinforced the Ti matrix and facilitated the formation of a stable and protective tribofilms. The tribofilms contained carbonaceous material that provided easier shear and lower friction. The formation of these tribofilms was highly dependent on the TiC particles, which contained excess carbon compared to the equilibrium composition. Higher TiC content was more effective in quickly developing and sustaining the tribofilms.