工艺参数对Ni60-Cu/BaF2·CaF2定向结构涂层组织和性能的影响

采用氧乙炔火焰喷涂+感应重熔+强制冷却相结合的复合技术制备了Ni60-Cu/BaF₂·CaF₂定向结构复合涂层,研究了感应重熔参数对Ni60-Cu/BaF₂·CaF₂定向结构复合涂层组织结构、元素分布、微观硬度的影响.研究表明:过低的感应重熔功率(7 kW)不能提供涂层足够的熔化热,不能保证涂层完全的熔融状态,过高的感应重熔功率(15 kW)导致过高的热输入,使基体元素向涂层过量扩散以及组织粗大,硬度降低.当感应重熔功率为10 kW时,定向结构涂层获得了良好的微观组织,涂层中组织致密且柱状晶明显,涂层与基体间的冶金结合带也较为平整,且涂层的硬度值较高.     

不同重熔处理对镍基自溶性粉末合金涂层构件疲劳性能的影响

为了研究重熔处理对构件疲劳性能的影响,以35#钢为基体,以镍基自熔性粉末合金为喷涂材料的热喷涂试样在电退火炉中进行3种不同时间的重熔处理后进行弯扭疲劳试验,应用扫描电子显微镜对不同试样的显微组织进行观察.结果表明:经不同重熔处理后涂层材料均在界面形成了明显的扩散层,涂层与基体的黏结强度高,使喷涂试样疲劳强度均高于基体试样;随着保温时间的延长,涂层中孔隙的大小及数量随之增多.同时,涂层中的Cr固化生成CrB和Cr7C3,导致整个涂层基体硬度降低.从而使裂纹优先在孔隙界面萌生,并沿较软基体扩展,最终使整个试样疲劳强度降低.     

感应重熔对高速轧机轴承热喷涂层微观组织性能的影响

为了改善高速轧机轴承热喷涂层的微观组织性能,采用感应重熔技术对GCr15轴承钢表面预制备的高能火焰喷涂Ni60A涂层进行感应重熔处理,并利用金相显微镜、扫描电镜、X射线衍射仪、显微硬度计对感应重熔前后涂层的孔隙率、微观组织、显微硬度等进行对比研究,探讨感应重熔对涂层以及界面微观组织、显微硬度的影响。结果表明,高能火焰喷涂镍基涂层的孔隙率高达5.09%,且表面孔洞缺陷较多,涂层与基体结合的界面处存在较明显的界面裂纹和孔隙缺陷,呈现典型的机械结合,界面结合特性较差;而经感应重熔后其涂层组织致密,孔隙率仅为0.27%,涂层缺陷明显减少,与基体结合的界面处呈现出强冶金融合特性,且涂层中硬质相数量显著增多,涂层及界面的显微硬度均得到较大提升。因此,感应重熔技术可改善涂层的表面组织性能,在高速轧机轴承表面强化方面有一定的应用价值。     

Al—Cu—Fe—B准晶材料断裂韧性的评估

采用(Vickers)压痕试验法来测试评估准晶Al59Cu25.5Fe12.5B3的断裂韧性.根据维氏压痕的断面轮廓、径向裂纹尺寸和相关的计算表达式,测试了显微硬度Hv和裂纹萌生的临界载荷值,评估了该准晶材料的杨氏弹性模量E和断裂韧性.结果表明该准晶材料的杨氏模量为108.5GPa,断裂韧性约1.34MPa*m-1/2.对于维氏压头而言,裂纹萌生的临界载荷值在250mN～500mN的范围.此外,运用原子力显微镜(AFM)和扫描电子显微镜(SEM)观察了裂纹萌生和裂纹扩展的表面形貌.     

激光工艺对45钢表面梯度熔覆层组织性能的影响

研究了激光熔覆功率、扫描速度和熔覆材料对熔覆层组织结构与耐磨性等的影响.结果表明:梯度熔覆层连续完整,无裂纹、气孔等缺陷,与45钢基体呈冶金结合状态.熔覆层显微组织特征为枝晶、等轴晶等多种形貌的快速凝固组织,由α-Fe,CrNiFe-C和Cr₇C₃等组成.熔覆层显微硬度呈梯度分布,表层硬度达7.48GPa,过渡层硬度达5.52GPa,分别是基体硬度的3.74和2.76倍.激光熔覆技术可显著提高45钢的耐磨性能.     

原位生成TaB_2颗粒增强镍基复合涂层的组织与耐磨性

以Ta粉、B粉和Ni60A粉为原料,利用氩弧熔覆技术在Q235钢基体表面制备原位生成TaB_2颗粒以增强Ni基复合涂层。通过金相显微镜、扫描电镜、X射线衍射仪、显微硬度计以及摩擦磨损试验机对复合涂层的显微组织、物相、显微硬度以及涂层耐磨性进行分析研究。结果表明,镍基复合涂层形成良好,没有气孔和裂纹等缺陷,涂层与基体呈现良好的冶金结合。熔覆层由原位生成的TaB_2颗粒相、Fe-Cr相及Cr_7C_3相组成。TaB_2颗粒弥散分布在基体上,氩弧熔覆涂层的平均显微硬度达到11.50 GPa,比基体Q235钢提高约4倍。在室温干滑动磨损条件下,该熔覆涂层的耐磨性比基体提高约12倍。     

镁合金表面氩弧熔覆Al-Si基SiC复合涂层组织及耐磨性

采用氩弧熔覆方法作为镁合金材料表面强化,是一项全新技术,在AZ31B镁合金基体表面制备10%Si C粉末+Al-Si合金粉末的复合涂层,利用X射线衍射仪、光学显微镜和扫描电子显微镜分析涂层的物相组成和显微组织;利用显微维氏硬度计和干滑动摩擦磨损实验机测试复合涂层在室温下的显微硬度和摩擦磨损性能。结果表明:氩弧熔覆涂层与基体界面具有良好的结合,无气孔、夹杂、裂纹等缺陷;熔覆层主要由Mg2Si、Mg2C3、Mg17Al12、Al3.21Si0.47等物相组成;熔覆层内部主要由黑色块状组织组成,尺寸为2~5μm;由于在氩弧熔覆过程中生成了新的物相使得涂层的显微硬度提高,涂层平均硬度可达2.5 GPa,是AZ31镁合金基体的4倍;基体的平均摩擦系数约为0.7,10%Si C氩弧熔覆层摩擦系数约为0.57,摩擦系数明显降低;熔覆涂层的相对耐磨性较基体提高近5倍。     

SiO2包覆对爆炸喷涂自敏涂层发光和摩擦性能的影响

采用溶胶-凝胶法在铝酸锶荧光粉表面包覆SiO₂层,以45号钢为基体,采用爆炸喷涂技术制备不同SiO₂包覆质量分数下的SrAl₂O₄∶Eu²⁺, Dy³⁺/Cu-14Al-X自敏复合涂层.对比研究了不同包覆质量分数下铝酸锶粉末与自敏涂层的发射光谱和余辉衰减曲线,复合涂层的摩擦系数与磨损量以及SiO₂包覆质量分数对自敏涂层的发光性能和摩擦学行为的影响.结果表明:SiO₂包覆使得铝酸锶在爆炸喷涂制备过程中得到了保护,提高了涂层的发光性能.随着SiO₂包覆质量分数的增加,复合涂层结构致密度、硬度和耐磨性提高.20%包覆质量分数下铝酸锶粉末硬度为564.5HV,比未包覆铝酸锶粉末的涂层提高了38%.由于破碎后的SiO₂包覆层具有自润滑效果,包覆后复合涂层的摩擦系数相对稳定,15%SiO₂包覆质量分数下复合涂层摩擦系数为0.182,具有最优的摩擦性能.     

重熔处理过程对镍基合金复合涂层的组织变化影响

采用超音速大气等离子喷涂方法,在Q235A钢基体上制备了含有20%WC的NiCrBSi复合涂层,并对涂层进行氧-乙炔火焰重熔处理。利用扫描电子显微镜对重熔前后的涂层进行微观结构分析,并采用X射线衍射方法研究其相组成。发现重熔处理后涂层中缺陷减少,WC、CrB和Cr7C3等硬质相被γ-Ni固溶体所包覆,对提高涂层的显微硬度和耐摩擦磨损性能有显著作用。     

沉积温度对AlTiN/AlTiSiN多层复合涂层的影响

为了优化AlTiN和AlTiSiN的沉积温度，兼顾2种涂层的性能，采用电弧离子镀膜技术，在不同沉积温度下，制备一系列AlTiN/AlTiSiN多层复合涂层，并采用SEM、XRD、EDS、纳米压痕仪、划痕仪、摩擦磨损试验机和轮廓仪等仪器对复合涂层的微观结构、力学性能以及摩擦学性能进行表征和测试，探究沉积温度对AlTiN/AlTiSiN多层复合涂层的影响.结果表明：(1)随着沉积温度升高，多层复合涂层的表面质量逐渐改善，组织结构更加致密；(2)随着沉积温度升高，涂层的纳米硬度和膜基结合强度先增大后减小，摩擦系数和磨损率先减小后增大；(3)当沉积温度为430℃时，涂层综合性能最好，硬度为30.9GPa，临界载荷为89N，摩擦系数为0.72，磨损率为7.1×10^-3μm³/(N·μm).     

超音速火焰喷涂制备双峰WC-12Co涂层组织性能研究

采用JP-8000型超音速火焰(HVOF)喷涂设备,在低碳钢基体上制备了双峰WC-12Co涂层,测试了涂层的结合强度、显微硬度、气孔率以及抗磨粒磨损性能.并利用XRD对喷涂粉末及涂层进行了相结构分析,用扫描电子显微镜对喷涂粉末、磨粒磨损后的涂层表面形貌进行了观察.结果表明:在喷涂过程中,仅有很少量的WC粒子发生氧化脱碳...     

螺杆泵螺杆纳米掺杂陶瓷涂层显微结构研究

利用大气等离子喷涂技术（APS）,在7.5m螺杆泵螺杆基体表面上制备纳米掺杂30%AT13(Al₂O₃+13%TiO₂)陶瓷涂层,采用Philips XL-30型扫描电镜（SEM）、能谱（EDS）和Philips X-port型X射线衍射仪（XRD）等现代分析手段对纳米掺杂AT13等离子喷涂粉末及螺杆表面等离子喷涂涂层的显微组织、物相进行了观察测定。结果表明：纳米掺杂等离子喷涂粉末结构呈微米级粒子表面包覆纳米粒子的麻团状,尺寸在50~70μm内,流动性好,适用于大气等离子喷涂。纳米掺杂使等离子喷涂涂层元素分布均匀性提高,孔隙度降低,涂层内出现（Al₂O₃）_5.333与斜方晶态的Al₂TiO₅物相。涂层断口分析证明：在纳米掺杂30%的涂层中,出现大量直径约为10nm的蠕虫状晶须,断裂方式变为韧性的穿晶断裂,为纳米掺杂螺杆使用寿命成倍的提高提供了理论依据。     

Mechanism of brittle-ductile transition of a glass-ceramic rigid substrate

The hardness, elastic modulus, and scratch resistance of a glass-ceramic rigid substrate were measured by nanoindentation and nanoscratch, and the fracture toughness was measured by indentation using a Vickers indenter. The results show that the hardness and elastic modulus at a peak indentation depth of 200 nm are 9.04 and 94.70 GPa, respectively. These values reflect the properties of the glass-ceramic rigid substrate. The fracture toughness value of the glass-ceramic rigid substrate is 2.63 MPa?m1/2. The material removal mechanisms are seen to be directly related to normal force on the tip. The critical load and scratch depth estimated from the scratch depth profile after scratching and the friction profile are 268.60 mN and 335.10 nm, respectively. If the load and scratch depth are under the critical values, the glass-ceramic rigid substrate will undergo plastic flow rather than fracture. The formula of critical depth of cut described by Bifnao et al. is modified based on the difference of critical scratch depth     

Mechanism of brittle-ductile transition of a glass-ceramic rigid substrate

The hardness, elastic modulus, and scratch resistance of a glass-ceramic rigid substrate were measured by nanoindentation and nanoscratch, and the fracture toughness was measured by indentation using a Vickers indenter. The results show that the hardness and elastic modulus at a peak indentation depth of 200 nm are 9.04 and 94.70 GPa, respectively. These values reflect the properties of the glass-ceramic rigid substrate. The fracture toughness value of the glass-ceramic rigid substrate is 2.63 MPa·m1/2. The material removal mechanisms are seen to be directly related to normal force on the tip. The critical load and scratch depth estimated from the scratch depth profile after scratching and the friction profile are 268.60 mN and 335.10 nm, respectively. If the load and scratch depth are under the critical values, the glass-ceramic rigid substrate will undergo plastic flow rather than fracture. The formula of critical depth of cut described by Bifnao et al. is modified based on the difference of critical scratch depth     

评价硬质涂层机械性能的技术

描述了测定硬质涂层与基体间的结合力、显微硬度、断裂强度、耐磨性以及涂层刀具切削寿命试验的方法和原理。涂层与基体间的结合力是一种界面特性、是涂层能否实用的关键因素之一。采用四点弯曲法、扭转法、划痕法和压痕技术对硬质涂层(TiN和TiC)的结合力进行测定和评价。硬质涂层的断裂强度、显微硬度和耐磨性也是它的重要机械性能指标,本文对这些性能的测试技术也进行了论述。同时还就硬质涂层刀具的切削寿命进行试验,对其实际的使用效果进行评价。     

Reinforcing effect of laminate structure on the fracture toughness of Al_3Ti intermetallic

Metal/intermetallic laminate composites can improve the mechanical properties of intermetallic materials using metal layers. In recent years, titanium aluminide intermetallics have received increasing attention due to their excellent performance properties, such as high melting point, high specific strength and stiffness, and good corrosion resistance. However, the low fracture toughness of Al_3Ti alloys at room temperature has greatly limited their application, and fiber or particle reinforcement has not shown a significant toughening effect. Research into the reinforcing effects of the interface and near-interface zone on the fracture behavior of Al_3Ti is lacking. Ti/Al_3Ti metal/intermetallic laminate composite was synthesized from titanium and aluminum foils using vacuum hot-pressed sintering technology. The microstructure of the prepared material was analyzed by scanning electron microscope and electron backscattered diffraction. Results illustrate that both Ti and Al_3Ti were single-phase and there was a noticeable stress concentration on the interface. To obtain indentation and cracks, loads were applied to different locations of the composite by a microhardness tester. The growth path of the cracks was then observed under microscope, showing that crack propagation was prevented by the interface between the Ti and Al_3Ti layers, and the cracks that propagated parallel to the laminate shifted to the interface. Fracture toughness of the different areas, including Al_3Ti layers, interface, and near-interface zone, were measured by the indentation fracture method. The fracture toughness at and near the interface was 1.7 and 2 times that of the Al_3Ti layers, respectively. Results indicate that crack blunting and crack front convolution by the laminate structure was primarily responsible for increased toughness.