Wear-resistant coatings produced by shock-wave compaction of powders

Wear-resistant metal-matrix composite coatings with a thickness of 1.5 mm were fabricated on low-alloy steel substrates by explosively generated shock waves. Starting materials were equivolume mixtures of WC or Cr₃C₂ powder mixed with either titanium or cobalt powder as a binder phase. Three different planar geometries were used, with powder layer thicknesses varying from 1 to 3 mm. Microstructural examination showed that fully dense, crack-free coatings could be produced with a uniform distribution of the carbides within the metallic binder phase. Shear strengths in excess of 40 MPa were measured for coatings composed of equivolume powder mixtures of (Cr₃C₂ + Ti) and (WC + Ti). The weight loss of a coating produced from an equivolume (WC + Co) powder mixture measured from a two-body abrasive wear test was significantly lower than that measured for a wear-resistant tool steel used as a reference material.     

Si-Ni-Fe alloys for magnetron sputtering targets

The effect of the cooling rate on the microstructure, micromechanical properties, and thermal residual stresses of magnetron sputtering targets made of cast resistance alloys Si-10% Ni-4% Fe and Si-15% Ni-6% Fe is studied. The optimum cooling rates of castings that provide a homogeneous fine-grained structure, high strength characteristics, and the minimum level of residual stresses in the targets are found.     

离子源辅助中频磁控溅射法在活塞环表面沉积CrN涂层

用热丝弧光放电离子源辅助的中频磁控溅射装置在单晶硅和渗氮钢质活塞环上沉积CrN涂层,并用X射线衍射、原子力显微镜和电子显微镜测量涂层的微结构,用显微硬度计和球盘式摩擦磨损仪测量涂层的硬度和摩擦性能。与常规的中频磁控溅射法相比,采用离子源辅助磁控溅射法制备CrN涂层的沉积速率提高30%以上,达到4.0μm/h。在靶基距为90 mm,氮气分压比为0.14的优化条件下,沉积在活塞环上的CrN涂层结构为CrN(200)取向,涂层厚度达到25μm,硬度高达17.85 GPa,平均摩擦因数为0.48。     

Microstructure of an Si-Cr-Co alloy for magnetron sputtering targets

The influence of the cooling rate on the microstructure of an Si-54% Cr-6% Co cast alloy for magnetron sputtering targets is discussed. The alloy contains highly brittle phases CrSi, CrSi₂ and Cr₃Co₅Si₂. It is experimentally established that the required quality of a cast target of the considered composition cannot be achieved at high cooling rates of the alloy. Slow cooling can be achieved using a heated casting mold by adjusting the alloy cooling rate. It has been demonstrated that the alloy has the most uniform structure and the lowest porosity at cooling rates in the range 0.5–5°C/s.     

Development of a hybrid process of obtaining wear-resistant coatings based on ion-plasma arc sputtering and magnetron sputtering

This work is devoted to the development of a new hybrid method of deposition of coatings based on ion-plasma arc sputtering and magnetron sputtering. The objects of investigation were samples of coatings of the Ti-Al-N system on the VK-6 hard-alloy plates obtained by three different methods, namely, ion-plasma sputtering, magnetron sputtering, and hybrid sputtering. Deposition processes were performed under the rarefaction of 1.3 × 10^?3 Pa at a substrate temperature of 550–600°C. A VT-5 alloy of the composition Ti-Al (6 at %) was used as the sputtered material. The phase and elemental compositions of the coatings, their mechanical properties (microhardness and the Young modulus), and adhesion strength were studied. All samples were tested under the conditions of continuous cutting. The results of investigations showed that the coating obtained by the hybrid method possesses a complex of positive properties of the ion-plasma and magnetron coatings, specifically, a high adhesion strength along with the uniformity of the composition and structure, which explains its increased durability.     

多弧-磁控溅射法制备Ti-Si-N纳米复合涂层及涂层的结构和力学性能

用内外靶配置的多弧-磁控溅射技术在单晶硅和硬质合金上制备Ti-Si-N纳米复合涂层,研究衬底偏压和Si靶溅射电流对涂层结构和力学性能的影响,经过实验参数优化,在偏压为-150 V、Si靶电流为15 A的沉积条件下,得到Si的原子分数为6.3%的Ti-Si-N纳米复合涂层。X射线衍射、X射线光电子能谱和透射电镜分析表明,涂层中含有晶态TiN和非晶Si3N4,纳米尺寸的TiN颗粒镶嵌在非晶Si3N4基体结构中。纳米硬度计测试表明涂层的显微硬度为40 GPa,摩擦学实验表明其摩擦因数为0.89,可满足Ti-Si-N纳米复合涂层的工业化应用要求。     

Wear-resistant bronze-base composite materials produced by electric-discharge sintering

Conclusions Sintered bronze-stellite and bronze-sormite materials produced by EDS are superior in frictional properties and wear resistance to BrO10 bronze. Under conditions of friction without lubrication the advantages of such bronze-stellite and bronze-sormite materials manifest themselves most clearly at high sliding speeds (in excess of 4 m/sec). In operation with lubrication the load-carrying capacity of a sintered bronze-sormite material is two and a half times that of BrO10 bronze.Translated from Poroshkovaya Metallurgiya, No. 9(213), pp. 6–8, September, 1980.     

Wear-resistant amorphous and nanocomposite steel coatings

In this article, amorphous and nanocomposite thermally deposited steel coatings have been formed by using both plasma and high-velocity oxy-fuel (HVOF) spraying techniques. This was accomplished by developing a specialized iron-based composition with a low critical cooling rate (≈10⁴ K/s) for metallic glass formation, processing the alloy by inert gas atomization to form micron-sized amorphous spherical powders, and then spraying the classified powder to form coatings. A primarily amorphous structure was formed in the as-sprayed coatings, independent of coating thickness. After a heat treatment above the crystallization temperature (568 °C), the structure of the coatings self-assembled (i.e., devitrified) into a multiphase nanocomposite microstructure with 75 to 125 nm grains containing a distribution of 20 nm second-phase grain-boundary precipitates. Vickers microhardness testing revealed that the amorphous coatings were very hard (10.2 to 10.7 GPa), with further increases in hardness after devitrification (11.4 to 12.8 GPa). The wear characteristics of the amorphous and nanocomposite coatings were determined using both two-body pin-on-disk and three-body rubber wheel wet-slurry sand tests. The results indicate that the amorphous and nanocomposite steel coatings are candidates for a wide variety of wear-resistant applications.     

Microporosity of powders produced by centrifugal sputtering

Conclusions The nature of the liquid-metal film flow about the end of the pulverized billet is defined by its rotational velocity. In the case of a turbulent film flow regime gas is captured and pores are formed in individual powder particles.The greatest number of porous particles produced in a single pulverization regime is found in a large-fraction powder while the smallest quantity is found in the finely dispersed powder with grain sizes less than 100n.Increasing the helium content in the pulverization medium to 100% produces a discontinuous increase in the number of porous particles as a result of the reduced viscosity of the gaseous medium and the high penetration power of the helium. The smallest number of porous particles is formed when pulverization takes place in a medium with a volumetric argon content in excess of 30%.The pore size in the powder particles is virtually independent of the production regime and usually amounts to about 25–35 % of the particle diameter. The average gas-pore volume is 2–3% of the volume of the powder particle.To achieve minimum microporosity in compacted billets fabricated by the methods of powder metallurgy, it is expedient to use 100m powder fractions, produced at a billet rotation velocity of 35–40 m/sec.Translated from Poroshkovaya Metallurgiya, No. 12(348), pp. 1–7, December, 1991.     

磁控溅射制备YBCO超导薄膜的AFM研究

采用中空柱阴极直流磁控溅射装置制备YBCO超导薄膜,应用原子力显微镜（AFM）研究了在最佳工艺条件下沉积在LaAlO3和Zr(Y)O2上的具有c轴取向的YBCO超导薄膜及其相应衬底的表面形貌,生长的YBCO膜都具有较好的表面结构,在LaAlO3单晶衬底上的YBCO膜形成大颗粒岛状结构,颗粒生长整齐,尺寸大小均匀;生长在单晶Zr(Y)O2上的YBCO膜则形成起伏较大的层状与岛状生长的混合结构,这些差别的产生与衬底的初始状况及制备过程中膜与衬底的界面作用有关。分析了形成超导薄膜不同表面形貌的原因,从生长机理角度讨论了表面形貌与缺陷和位错的形成机制。     

镁合金表面磁控溅射沉积铝膜的力学性能

采用直流磁控溅射法在镁合金上沉积铝膜,在高真空下对铝膜进行加热后处理.用X射线衍射仪(XRD)分析膜层为纯铝多晶态,扫描电子显微镜(SEM)观察铝膜晶粒细小.采用纳米压痕/划痕仪对铝膜的厚度、临界附着力、硬度和弹性模量进行了测试,并且用辉光放电光谱仪(GDS)测试了镁合金表面铝膜的成分和性能随薄膜深度的分布.结果表明,铝膜的厚度随后处理温度的升高而降低,其表面硬度和弹性模量高于镁合金基体并且随深度增加而逐渐降低.铝膜与镁合金基体间存在一个过渡层,结合良好且表现出一定的弹塑性能,有利于镁合金表面的防护.     

Analysis of the composition of Sr -Bi-Ca-Cu-Pb-O films obtained by magnetron sputtering

The composition of thin films of superconducting Sr-Bi-Ca-Cu-Pb ceramic, deposited by magnetron sputtering from targets prepared from oxide powders of the corresponding elements, was investigated. It was found that the film composition differs from that of the target. Microprobe analysis of target and films can be used to determine the correct target composition for the deposition of a superconducting film.Materials Science Institute, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 5–6, pp. 27–30, May–June, 1996. Original article submitted May 25, 1994.     

SHS—离心法制备铁—铬—镍合金的耐蚀性能

利用ＳＨＳ－离心法制备铁－铬－镍合金内衬复合钢管，系统研究内衬层的耐蚀性能，结果表明，含碳量较低的ＳＨＦ耐蚀合金在硫酸中的耐蚀性优于１Ｃｒ１８Ｎｉ９不锈钢，具有优异的抗点蚀和抗均匀腐蚀性能，但抗晶间腐蚀性能较差，也不耐盐酸腐蚀。     

Wear-resistant P/M titanium carbide - iron coatings

Conclusions In thw work described the electric contact sinter-bonding process was employed for applying, to type 45 steel, TiC-iron composite coatings exhibiting high hardness (up to 550 HV), low porosity (0.45%), and good adhesion to their bases (up to 12 · 10⁷ N/m²). The abrasive wear resistance of the materials of these coatings proved to be twice as high as that of quenched type 45 steel. The electric contact s inter-bonding method of application of coatings enables uncomminuted coarse powders to be employed and ensures high rates of coating application (the optimum sinter-bonding time is 0.16–0.18 sec, the weight rate of coating application being 5 kg/h). Coatings applied by the electric contact sinter-bonding method can be employed for building up worn surfaces of components of, e.g., agricultural machines.Translated from Poroshkovaya Metallurgiya, No. 11(215), pp. 39–42, November, 1980.