氩弧重熔对Q235钢B-C-N渗层冲蚀磨损性能的影响

研究了氩弧重熔对Q235钢B-C-N共渗层的组织结构、水冲蚀磨损及海水介质腐蚀磨损性能的影响。XRD分析显示,共渗层由FeB、Fe2B、Fe3B、Fe2N、Fe8N和Fe3C相组成,氩弧重熔层由Fe2B、Fe3N、Fe8N、Fe3C和Fe23(B,C)6相组成;共渗层显微硬度最高值为1198.4HV,重熔层最高硬度值为1192.8HV,但硬度梯度变化平缓;在水介质冲蚀及海水介质腐蚀磨损试验中,重熔层的耐磨性均优于共渗层。     

FeB和Fe2B价电子结构与钢表面渗硼层硬化本质

依据EET理论,计算了FeB和Fe_2B价电子结构并分析了它们与钢渗硼层硬化的关系。研究发现:渗硼表面改性后,钢表面硬度和耐磨性提高的根本原因在于FeB和Fe_2B最强键的键合力远大于基体α-Fe最强键的键合力;FeB的硬度比Fe_2B大的微观本质在于FeB相最强键的键合力、主键络连接键的键合力和共价电子密度分别比Fe_2B的大27.12%、4.8%和3.66%;FeB相比Fe_2B脆性大的微观本质在于FeB共价键空间分布更不均匀,FeB相主键络具有较强的共价性,而Fe_2B相主键络具有较强的金属性;由于FeB相成键能力仅比Fe_2B的成键能力大0.85%,因此优先形成的Fe_2B相极易转变为FeB相,使得钢表面渗硼层的脆性增强。     

激光重熔处理对渗硼层脆性的影响

利用两种工艺方案对渗硼层进行了激光重熔处理，并通过声发射技术对表层脆性进行了定量测试。结果表明，激光重熔处理在不同程度上降低了渗硼层的脆性，相对脆性最大降低了71．3％。通过改变渗硼层的形貌和组织结构，消除FeB和渗层内的缺陷，改善界面结合强度和适当降低表层硬度从而使硼原子得到重新分布等方式均能降低表层脆性。     

大气等离子喷涂Fe基涂层及其氩弧重熔层的组织与力学性能

采用氩弧重熔技术对大气等离子喷涂Fe基涂层进行了重熔处理,分析了重熔前后涂层的显微组织和力学性能。结果表明,重熔后Fe基喷涂层的层状结构以及气孔、未熔颗粒、夹杂物基本被消除,孔隙率由4%降低到0. 4%,重熔层组织致密。喷涂层主要由微晶区、纳米晶区和过渡区组成,结晶度较差,原子排列较混乱,而重熔层由单晶区和(Fe,Cr)23C6相构成,析出相与基体界面处无显微裂纹,结晶度较好,原子排列较规则;喷涂层与基体结合处有明显缝隙,结合方式为机械结合,而重熔层与基体界面产生"白亮带",结合方式为冶金结合;相对于喷涂层,重熔层的平均显微硬度和弹性模量分别提高了33. 4%和53. 2%,表面粗糙度降低了43. 2%。氩弧重熔处理显著地改善了Fe基涂层的显微组织及力学性能。     

渗硼注氮复合处理表面硬化层研究

采用渗硼工艺和新型的等离子体源氮离子注入技术对Cr12MoV钢进行复合处理 ,获得了高硬度的表面硬化层。用XPS对硬化层进行相分析和性能试验 ,结果表明 :硬化层主要由立方氮化硼 (C BN)和FeB组成 ,硬化层具有很高的硬度和耐磨性     

GCr15钢表面激光硼化研究

在已经过常规淬火的GCr15轴承钢表面,利用脉冲Nd∶YAG激光进行了B4C粉末硼化改性处理.采用扫描电子显微镜、X射线衍射仪、显微硬度仪及摩擦磨损试验仪器对激光硼化处理后改性层的显微组织及性能进行了研究.结果表明:激光硼化改性层由树枝晶的FeB、Fe2B和基体组成,改性层的表面硬度高达HV1560,相比处理前硬度提高了81.8％,硬化层深度约为150μm,磨损率相比处理前降低了67.55％,激光硼化后GCr15钢表面的硬度和耐磨性能显著提高.     

稀土对H13钢固体渗硼层高温摩擦磨损性能的影响

研究了稀土氯化物CeCl3添加量对H13钢固体渗硼层截面形貌、显微硬度、表面粗糙度以及相组成的影响,以及稀土催渗辅助渗硼H13钢的高温摩擦磨损性能。结果表明:添加2.5%和5%的稀土显著提高渗硼层厚度、显微硬度与致密性,但是表面粗糙度略有提高;10%稀土渗硼试样的渗层最厚,但是其显微硬度、致密性明显下降,表面粗糙度提高;稀土辅助渗硼层中除Fe2B相外还出现了(Fe,Cr)2B相;与不加稀土渗硼试样相比,5%稀土渗硼试样的渗层磨穿时间约增加一倍,磨损率降低21%;5%稀土渗硼试样磨损率比未渗硼H13钢降低了61%,并且也低于10%稀土渗硼试样。因此,加入5%稀土催渗辅助渗硼H13钢的高温耐磨损性能较优。     

PIII技术制备c-BN硬化层

采用一种新型的等离子体浸没式离子注入技术(PIII)在渗硼后的50Mn钢试样上制备出了厚度为0.15~0.2mm的立方氮化硼(c-BN)表面硬化层。经X光电子能谱(XPS)和X光衍射分析(XRD),发现硬化层中的组织有立方氮化硼(c-BN)、六方氮化硼(h-BN)、B2O3、FeB和Fe2B。在表层60nm的深度范围内,c-BN的含量较高。采用球盘式无润滑滑动摩擦试验和维氏显微硬度试验分别对渗硼+PIII复合处理以及单独渗硼的50Mn钢试样的性能进行了对比试验。结果表明,与单独渗硼的试样相比,渗硼+PIII复合处理的试样具有高得多的硬度(高达Hv0.1N44GPa)和耐磨性。该项技术在电缆压模上进行了应用试验,获得了较好的应用效果。     

冷却速率对包埋渗B的组织和性能的影响

为掌握粉末包埋渗硼(B)工艺后冷却方式对其组织性能影响规律,采用粉末包埋法在40Cr基体表面制备了渗B层,利用X射线衍射仪、场发射扫描电子显微镜、能量色散光谱仪、显微硬度测试仪、摩擦磨损试验仪等研究了炉冷、空冷、液氮冷和水冷条件下渗B层的物相、界面组织和性能.结果表明:冷却速率对渗B层组织形貌影响很小,所有渗层均由Fe2B柱状晶粒组成,但随着冷却速率的增加,渗B层逐渐出现微裂纹;存在一临界冷却速率vc(100℃/s＜vc＜1 000℃/s),能够改变Fe2B晶粒的择优取向生长;炉冷条件下的渗B层有最高的平均硬度、致密度以及最优的耐磨性.     

硼对熔盐电沉积渗硅层成分及组织结构的影响

选取无硼(NaCl-KCl-NaF-SiO2)和含硼(NaCl-KCl-NaF-SiO2-Na2B4O7)两种熔盐通过电沉积的方法在纯铁表面制备了渗硅层.利用辉光放电光谱仪、扫描电镜(SEM)和X射线衍射仪(XRD)对渗硅层渗入元素的含量与分布、表面形貌及物相组成进行了检测分析.结果表明,硼的加入起到了明显的催渗作用,含硼试样渗层较厚,硅分布均匀;表面平整、致密,晶粒细小;含硼试样由Fe2B及Fe3Si组成,无硼试样由Fe3Si及Si在α-Fe中的固溶体α-Fe(Si)组成,硼的加入降低了Fe3Si的有序度.     

高硬度耐磨损电弧喷涂涂层研究

采用电弧喷涂方法制备的高硬度耐磨损JCW-B涂层可广泛应用于工业零部件耐磨表面.对涂层的组织、孔隙率、硬度、结合强度及耐磨粒磨损性能进行分析,对比研究该涂层与Ni60喷熔层的耐冲蚀性能.结果表明JCW-B涂层组织致密,孔隙率低于4%,显微硬度HV0.1高于1200,平均结合强度大于50MPa.研究了涂层的耐磨损机理,XRD结果显示涂层中主要含有Fe3B硬质相,对涂层起到弥散强化的作用.     

Al2O3对氩弧熔覆Fe-Si金属间化合物涂层组织及性能的影响

目前Fe-Si涂层的相关研究较少。为制备Fe-Si金属间化合物复合涂层并改善其力学性能,采用氮弧.熔覆原位合成的方法在Q235钢表面制备Fe-Si涂层和Fe-Si/Al2O3金属间化合物复合涂层,利用金相电子显微镜、X射线衍射仪(XRD)、冲蚀磨损试验机、高温氧化炉等设备对涂层的显微组织、耐冲蚀磨损性能和抗高温氧化性能进行测试与分析。结果表明:Fe-Si熔覆层由Fe3Si和FeSi相构成,添加A12O3后熔覆层除存在Fe3Si,FeSi外还有AI2O3相产生;Fe-Si/Al2O3熔覆层耐冲蚀磨损性优于Fe-Si熔覆层,最高为基体的4.65倍;熔覆层的耐高温氧化性能相对基体明显提高,在800℃下Fe-Si熔覆层和Fe-Si/Al2O3熔覆层相比于基体分别提高了5.50和5.83倍。     

Characterization of borided Incoloy 825 alloy

Incoloy 825 alloy is an alloy with high corrosion resistance but it has low strength and hardness. Increasing of hardness of the alloy is important for its wear resistance. In this study, Incoloy 825 alloy was boronized to increase its hardness. The boronizing process was carried out using the box boronizing method at 900 and 950 °C for 2, 4 and 6 h. The coating thickness that occurred by boronizing increased with the increase in temperature and time. The thickness of boride layers depending on temperature and process time was ranged from 35 to 170 μm. The presence of borides (e.g., FeB, Fe₂B, CrB, NiB) was confirmed by X-ray diffraction (XRD) analysis technique. The boron compounds have shown the random distribution. The microhardness has decreased along the coating thickness (towards to the matrix).     

氩弧熔覆Fe-Al金属间化合物复合涂层的组织与性能

为改善Fe-Al金属间化合物的力学性能及抗高温氧化性能,利用氩弧熔覆方法在Q235钢上制备了Fe-Al熔覆层和Fe-Al/Al_2O_3熔覆层。采用金相显微镜、X射线衍射仪、硬度计、磨粒磨损试验机对氩弧熔覆涂层进行显微组织结构观察和磨损性能测试。采用高温氧化试验对涂层的耐高温氧化性进行了研究。结果表明:Fe-Al熔覆层形成FeAl和Fe_3Al相,而Fe-Al/Al_2O_3熔覆涂层含有FeAl、Fe_3Al和Al_2O_3相;熔覆层的耐磨粒磨损性能优于基体且Fe-Al/Al_2O_3熔覆层优于Fe-Al熔覆层;熔覆层的耐高温氧化性能明显提高,在700℃下,Fe-Al熔覆层和Fe-Al/Al_2O_3熔覆层相比于基体分别提高了4.46和5.68倍。     

渗硼层形成机理的探讨

渗硼层的形成机理,一直是渗硼研究的重要课题。本文主要采用X射线法对用气体法在工业纯铁上形成渗硼层的过程进行了研究。结果表明,在渗硼时,依次形成硼的固济体,Fe_2B、FeB。即渗硼层形成过程完全符合相图和相律。     

Production of ferroboron powders by solid boronizing method

Ferroboron is an iron-boron alloy containing 10–20% of boron by weight. Commercial ferroboron production is made by two main processes: carbothermic reaction and aluminothermic reaction. Ferroboron also occurs in steel surfaces due to boronizing, which is applied to increase surface hardness in steel. Boronizing is a thermo-chemical surface hardening treatment. The ferroboron phases like Fe₂B, FeB form by diffusing of boron element into iron. These phases are very hard, wear strengths are high, and friction coefficients are low.In this study, ferroboron powder was obtained by boronizing ASC 100.29 iron powder that was used widely in powder metallurgy area. Solid boronizing method was preferred due to its advantages in applications and Ekabor-HM powder was used as the boronizing agent. The 80% ASC 100.29 and 20% Ekabor HM were mixed homogeneously and subjected to boronizing at 850–950 °C for 1–6 h. Formation and development of ferroboron phase on the samples was determined by metallographic studies depending on various treatment conditions. The X-ray diffraction analysis revealed that the Fe₂B phase did form but FeB phase did not. Micro hardness distributions were measured on the powder grains. Eighteen GPa hardness was measured at Fe₂B phase obtained by boronizing while hardness of non-boronized iron powders was 1.06 GPa. The thickness of ferroboron layer formed by boronizing changed with boronizing conditions. The thickness of ferroboron layer increased with boronizing temperature or boronizing time. Depending upon processing parameters, ferroboron layers was formed partially or throughout ferrous powder structure. Since boronizing can be applied to iron powders having any size or shape, ferroboron production with required shape and size is possible.Finally, a new method, namely solid boronizing method, was developed in ferroboron powder production.     

Laser Surface Strengthening Process of Al-Si Base Alloy

With a laser beam, the surface remelting/resolidifying treatment of ZL108 alloy was studied. Test results showed that a compact remelting layer was obtained with appropriate laser processing conditions and a suitable surface coating for laser energy absorption. The eutectic silicon phase in the laser-treating zone changed from the shape of thick-plate (stripe) into the very small grains, the structure was extremely fined, the hardness and wear resistance were improved greatly compared with that of the base alloy. A laser -treating layer, which is 3.5 mm thick and 5 mm wide, could be obtained.