原位生成TiC/Cr19Al3钢结硬质合金材料的制备与性能

以钛铁粉、铬铁粉、铁粉、胶体石墨等为原料,原位反应生成TiC/Cr19A13钢结硬质合金.并对所制备的试样进行组织结构分析.结果表明:反应生成的钢结硬质合金主要相组成为TiC Fe-Cr固熔体,所生成的硬质相TiC颗粒细小,随烧结温度升高TiC颗粒略有长大.当加入一定的钼与硼后,钢结硬质合金的致密度和硬度提高,TiC颗粒尺寸减小,分布更均匀.     

原位反应合成TiC/Cr18Ni8不锈钢钢结硬质合金组织结构

以铁粉、钛铁粉、铬铁粉、胶体石墨和镍粉等为原料,原位反应合成了TiC/ Cr18Ni8不锈钢钢结硬质合金,并用SEM、XRD、显微硬度计等对烧结试样进行显微组织和显微硬度分析.结果表明,钢结硬质合金主要组成相为TiC和Fe-Cr-Ni固溶体,硬质相TiC颗粒细小,形状规则,大部分在1 μm以下;随烧结温度的升高,钢结硬质合金的孔隙度减小,密度和硬度升高,但TiC颗粒略有长大.在相同烧结条件下,C/Ti成分克原子比为0.9的钢结硬质合金的密度和硬度比C/Ti成分克原子比为1.0的钢结硬质合金高,所合成的TiC颗粒更细小,分布更均匀.     

原位生成TiC／Cr19A13钢结硬质合金材料的制备与性能

以钛铁粉、铬铁粉、铁粉、胶体石墨等为原料,原位反应生成TiC／Cr19A13钢结硬质合金,并对所制备的试样进行组织结构分析。结果表明：反应生成的钢结硬质合金主要相组成为TiC＋Fe-Cr固熔体．所生成的硬质相TiC颗粒细小,随烧结温度升高TiC颗粒略有长大。当加入一定的钼与硼后,钢结硬质合金的致密度和硬度提高,TiC颗粒尺寸减小,分布更均匀。     

TiC含量对微波烧结钢结硬质合金组织及性能影响

以铁粉为基体,TiC颗粒为增强相,通过球磨、压制成型,微波烧结制备出TiC钢结硬质合金。结果表明,在1400℃微波烧结时,TiC颗粒与Fe具有良好的润湿性和流动性。随TiC含量升高,合金的晶粒逐渐变得均匀细小,合金的相对密度、显微硬度和抗弯强度均先升高后下降,相对密度和抗弯强度在TiC含量5%时达到最高值,分别为94.61%和1327.20 MPa,显微硬度在TiC含量10%时达到最高值,为760 HV。随TiC含量增加,钢结硬质合金的断裂方式由韧性断裂向脆性断裂过渡。     

(Ti,V)C原位烧结钢结硬质合金热处理后的组织与性能

以钛粉、钒铁粉、铬铁粉、钼铁粉、铁粉及石墨粉为原料,在真空烧结炉中原位合成了(Ti,V)c钢结硬质合金.研究了(Ti,V)C钢结硬质合金的热处理组织及力学性能.结果表明,该钢结硬质合金在1000℃淬火后的组织为片状马氏体+(Ti,V)C硬质相颗粒+少量未溶碳化物;经1000 ℃淬火+500℃回火时发生二次硬化现象,硬度达86 HRA左右,抗弯强度达1540MPa,其断口形貌为硬质相解理、基体准解理及韧窝;经1000℃淬火+250℃回火、1000℃淬火+500℃回火后该硬质合金的耐磨性分别是经深冷处理高铬铸铁的3.8和3.5倍,其磨损机理是基体形变磨损和硬质相脱落.     

钢结硬质合金中的硬质相

钢结硬质合金由硬质相和合金钢基体相构成,其所含硬质相的性质影响着钢结硬质合金的性质。本文讨论了硬质相的性质、硬质相同钢基体的相互作用以及硬质相数量的变化对合金性能的影响。这些硬质相包括WC,TiC,WC-TiC,Mo_2C,TaC,NbC,TiB_2等,其中以TiC,WC作硬质相的钢结硬质合金已有许多牌号。而Ti(C,N)钢结硬质合金还在研究之中,国外已有这方面的报道。除WC,TiC以外的其它硬质相在硬质合金中表现出不同的性质,但这是否适合于钢结硬质合金还有待于进一步研究。     

铸造烧结TiC钢结硬质合金/多元低合金钢复合界面及组织的研究

在研究烧结坯体压制工艺和铸造烧结工艺的基础上,采用铸造烧结法在多元低合金钢基体上,复合了2～4mm厚的铸造烧结TiC钢结硬质合金层.利用扫描电子显微镜和XRD等方法研究了烧结结合界面以及复合层组织和成分.结果表明:铸造烧结TiC钢结硬质合金复合层与基体材料结合界面存在明显的过渡层,为冶金结合;铸造烧结层中硬质相主要为TiC颗粒,其形状近似球形,颗粒直径在0.5～2 μm,体积分数约为50％～60％,均匀分布在粘结相中;粘结相为Fe-Cr的固溶体,含有少量Cr3C2和Cr7C3等烧结过程中形成的碳化物.     

原位反应合成稀土改性TiC钢结硬质合金的组织与性能

以钛铁粉、纯钼粉、纯铬粉、鳞片状石墨粉、羰基铁粉等为原料,采用原位反应合成的方法制备了TiC钢结硬质合金。采用丁苯橡胶和环烷酸稀土的混合物为成形剂,以引入稀土Ce元素对烧结材料进行改性。采用扫描电子显微镜(SEM)观察了烧结合金的显微组织,并对合金的密度(相对致密度)、硬度、极限抗弯强度进行了检测。结果表明:加入稀土元素后,烧结合金组织中的碳化钛颗粒均匀而细小,合金的密度(相对致密度)提高了3%;抗弯强度达到了1 780 MPa,比未加稀土元素的烧结合金提高了22%左右。因此,在原位反应合成中,稀土元素能够显著细化合金的组织并提高了烧结材料的性能。     

合金粉粒埋弧堆焊TiC颗粒增强铁基复合涂层

以TiFe粉、铬粉、镍粉、铁粉、胶体石墨等为原料,利用合金粉粒埋弧堆焊技术在Q235钢表面原位反应合成了TiC颗粒增强铁基复合涂层.无需焊前预热及焊后缓冷,且涂层无裂纹、夹杂、气孔等缺陷.利用SEM,XRD和EDS等试验技术分析了涂层显微组织,并用显微硬度计测试了硬度.结果表明,利用合金粉粒埋弧堆焊技术,可以原位合成细小弥散分布的TiC颗粒,尺寸在2μm以下.TiC颗粒增强铁基复合涂层组织大部分为马氏体组织、少量奥氏体组织和少量TiC颗粒构成.TiC颗粒不仅存在于奥氏体中,也存在于马氏体中.涂层平均显微硬度达601 HV0.2,约是碳钢基体的3倍.     

TiC-高锰钢结硬质合金显微组织分析

借助于光学显微镜、扫描电子显微镜、电子探针等手段,对TiC-高锰钢结硬质合金的组织、元素分布、硬度和断口形貌进行了分析研究.结果表明,TiC-高锰钢结硬质合金中的硬质相TiC颗粒细小且分布均匀;液相烧结过程中,Mo原子从铁基合金中扩散到TiC颗粒边缘,形成包覆结构,可改善液相对TiC的润湿性:同时这种结构可抑制TiC颗粒的互相靠拢,不至于过分长大,起到了细化碳化物粒子的作用.     

Microstructure of reactive synthesis TiC/Cr18Ni8 stainless steel bonded carbides

TiC/Cr18Ni8 steel bonded carbides were synthesized by vacuum sintering with mixed powders of iron, ferrotitanium, ferrochromium, colloidal graphite and nickel as raw materials. The microstructure and microhardness of the steel bonded carbides were analyzed by scanning electron microscope (SEM),X-ray diffraction (XRD) and Rockwell hardometer. Results show that the phases of steel bonded carbides mainly consist of TiC and Fe-Cr-Ni solid solution. The synthesized TiC particles are fine. Most of them are not more than 1 μm With the increase of sintering temperature, the porosity of TiC/Cr18Ni8 steel bonded carbides decreases and the density and hardness increase, but the size of TiC panicles slightly increases. Under the same sintering conditions, the density and hardness of steel bonded carbides with C/Ti atomic ratio 0.9 are higher than those with C/Ti atomic ratio 1.0.The TiC particles with C/Ti atomic ratio 0.9 are much finer and more homogeneous.     

Effects of nano TiN addition on the microstructure and mechanical properties of TiC based steel bonded carbides

TiC based steel bonded carbides with the addition of nano TiN were prepared by vacuum sintering techniques.The microstructure was investigated using scanning electron microscopy（SEM） and transmission electron microscopy（TEM）,and the mechanical properties,such as bending strength,impact toughness,hardness,and density,were measured.The results indicate that the grain size becomes small and there is uniformity in the steel bonded carbide with nano addition;several smaller carbide particles are also found to be inlaid in the rim of the larger carbide grains and prevent the coalescence of TiC grains.The smaller and larger carbide grains joint firmly,and then the reduction of the average size of the grains leads to the increase in the mechanical properties of the steel bonded carbides with nano addition.But the mechanical properties do not increase monotonously with an increase in nano addition.When the nano TiN addition accounts for 6-8 wt.% of the amount of steel bonded carbides,the mechanical properties reach the maximum values and then decrease with further increase in nano TiN addition.     

TiC—50Nb钢结硬质合金退火态组织的TEM研究

运用TEM研究了TiC-50Nb钢结硬质合金的退火态组织、发现该合金退火态显微组织为:TiC硬质相和由铁素体与M_(23)C_6碳化物构成的球状珠光体。其中TiC边界存在着小凸起,接近TiC处的M_(23)C_6碳化物较少。     

铸造烧结Fe—TiC表面复合材料的制备及其耐磨性原因

运用铸造烧结技术，在铸铁件表面合成了厚度为3～4mm的Fe-TiC表面复合材料，该表面复合材料中同时含有铬的碳化物和大量的TiC颗粒，表面复合材料的硬度由表及里逐步降低，在重载干滑动磨损条件下，表面复合材料显示了良好的耐磨性。     

碳化钛高锰钢结硬质合金的碎裂成因

利用扫描电镜与金相观察等分析方法 ,研究了碳化钛高锰钢结硬质合金在焊接和使用过程中产生裂纹与碎片的成因。结果表明 ,当硬质相 (TiC)之间的粘结相成分Mn ,Fe等元素含量偏低时 ,则粘结相的相对含量明显减少 ,粘结效果变差 ,致使硬质相在烧结过程中发生邻接和聚集长大 ,晶粒出现不均匀粗化 ,导致合金微区强韧性降低 ,在焊接应力 (或外力 )作用下容易产生微裂纹 ,若应力 (或外力 )进一步增大或作用时间延长 ,微裂纹将迅速扩展形成宏观裂纹进而脆裂成碎片。提出了在烧结过程中避免粘结相挥发、流失及硬质相邻接长大的工艺措施 ,以改善合金的组织与性能 ,防止产生裂纹与碎片。     

Microstructure of a Ni Matrix Composite Coating Reinforced by In-situ TiC Particles Using Plasma Cladding

THE TECHNOLOGY of a metal matrix composite(MMC)coating reinforced by ceramic particles oncheap metal substrates is a newly developed process.A powder alloy with a desirable composition is put onthe surface of a substrate.The powder and the toplayer of the substrate are simultaneously melted andrapidly solidified to form a dense coating and bondedtogether.Up to now,many cladding processes havebeen developed,including laser cladding'1'21,electroncladding and plasma cladding.The laser cladd…     

电冶稀土WC钢结硬质合金中碳化物特征的研究

采用电渣熔铸冶金工艺,用回收的碳化钨钢结硬质合金作原料,再加入微量的稀土,制备了新型的钢结硬质合金。用透射电镜、扫描电镜、金相显微镜及X射线衍射等测试手段研究了新材料中的碳化物的特征。结果表明：在该材料的显微组织中存在原始颗粒区和扩散区。原始颗粒区组织中碳化物的特征是存在大量变化甚微的角状大尺寸原始WCp及具有明显反应层的长椭圆状WC颗粒,界面反应产物为Fe3W2C。在粗大碳化钨颗粒附近能够原位生成先共晶析出相（WC和W2C）,在较远处的钢基体中分布着细网状碳化物,同时有（Cr,Fe）7C3等条状复式碳化物生成;而扩散区主要细小W2C小颗粒、WC颗粒及再结晶W-Fe-C小颗粒组成。稀土的加入可提高WC颗粒分散性。     

TiC-Maraging stainless steel composite： microstructure, mechanical and wear properties

Particulate TiC reinforced 17-4PH and 465 maraging stainless steel matrix composites were processed by conventional powder metallurgy （P/M）. TiC-maraging stainless steel composites with theoretical density 〉97% were produced using conventional P/M. The microstructure, and mechanical and wear properties of the composites were evaluated. The microstructure of the composites consisted of （core-rim structure） spherical and semi-spherical TiC particles depending on the wettability of the matrix with TiC particles. In TiC-maraging stainless steel composites, 465 stainless steel binder phase showed good wettability with TiC particles. Some microcracks appeared in the composites, indicating the presence of tensile stresses in the composites produced during sintering. The typical properties, hardness, and bend strength were reported for the composites. After heat treatment and aging, an increase in hardness was observed. The increase in hardness was at- tributed to the aging reaction in maraging stainless steel. The specific wear behavior of the composites strongly depends on the content of TiC particles and their interparticle spacing, and on the heat treatment of the maraging stainless steel.