Surface & Coatings Technology
Ti-B-N coatings were deposited on W18Cr4V high speed steels by using EB-ion plating with different boron contents. The chemical compositions of the coating are Ti, B and N. It was found that Ti, B and N in the coating are homogeneous, but there exists a diffusion zone at the coating/substrate interface on the basis of the results of ion probe microanalysis and Auger electron spectrometry. The boron content of the coating is 3-16 at.% given by nuclear reaction analysis. The ratio of nitrogen to titanium of the coating is about 1 given by electron probe microanalysis. The microhardness (HV) of the coating is 35-45 GPa (load of 0.25 N). The critical load of the coating using the scratch test is 12-14 N. The sliding friction coefficient of the coating on diamond stylus is 0.086-0.097 (load of 8.8 N). X-ray diffraction measurement shows that the coating consists of f.c.c. TiN, simple orthorhombic TiB, cubic BN and simple hexagonal Ti-B-N phases. As expected, the higher the boron content, the higher the content of cubic BN and TiB phases; and the higher the microhardness, the lower the adhesion.
关键词:
composition;property;EB-ion plating;Ti-B-N coating;tribological properties;hard coatings;behavior;film;gas
Journal of Applied Physics
Amorphous BC2N powders were prepared by mechanical milling with hexagonal boron nitride and graphite as starting materials. A bulk amorphous BC2N compound was produced by sintering the as-milled amorphous BC2N powders in a vacuum of 10(-5) Torr at a temperature of 1470 K. The conductivity measurement for the bulk amorphous BC2N compound showed that it behaves as a semiconductor with band gap energy of 0.11 eV for temperatures ranging from room temperature to 560 K and a semimetal for temperatures between 560 and 740 K. The mechanism of the formation of the amorphous BC2N powders is discussed. (C) 1998 American Institute of Physics.
关键词:
bc2n
Surface & Coatings Technology
Ti-B-N films were deposited on W18Cr4V high speed steels by using N ion bombardment on an electron beam ion plated Ti-B film. Scanning electron microscopy and transmission electron microscopy morphology of the samples shows that the films are found to have a dense and fine nanocrystalline structure, and a dense close interface bonding exists between the film and the substrate. Auger electron spectroscopy depth profiling analysis of the film indicates that N and Ti penetrate into the substrate, resulting in a wide interfacial diffusion zone, which is about 150 nm. Microdiffraction patterns of the interface show that FeTi, Fe2Ti, and Ti2N phases exist in the interfacial diffusion zone. The results obtained indicate that the method of bombarding the him by N ions extends the film-substrate interfacial diffusion zone and stimulates the interfacial chemical reaction.
关键词:
interfaces;ion bombardment;microstructure;coatings
Fatigue & Fracture of Engineering Materials & Structures
Fatigue crack growth behavior in welded joints subjected to elastic-plastic shock waves was investigated using three-point-bend specimens. The results indicate that the fatigue crack growth rate is reduced in the affected region of elastic or plastic waves. The travel of a plastic stress wave reaches 10 to 13 mm depth, but the hardness in this region is not increased although the lattice distortion is high. The crack path morphologies were observed, and reasons for a decrease in crack growth rate are presented.
关键词:
Shaohua Dong Weijian Han Yongming Luo Tong Zhao Caihong Xu
材料科学技术（英文）
Three new borazine derivatives, 2,4,6-tri(allylamino)borazine (CH2=CHCH2NHBNH)3 (1), 2,4,6-tri(3-ethynylanilino)borazine (CH´CC6H4NHBNH)3 (2), and 2,4,6-tri(4-propargyl oxyanilino)borazine (CH´CCH2OC6H4NHBNH)3 (3) were synthesized by reaction of 2,4,6-trichloro-borazine Cl3B3N3H3 (TCB) with corresponding primary amines, respectively. Their thermal behavior was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). These molecules were easily crosslinked via thermal
polymerization of reactive ethynyl or vinyl groups. The pyrolytic residues of borazines were investigated by X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and scanning electron microscopy (SEM). The analytic results indicated that B-C-N ceramics were formed upon pyrolysis of the borazines under an inert atmosphere.
关键词:
Precursors
,
Thermal properties
,
B-C-N ceramic
Zhidong ZHANG+
,
Changheng WU
,
Zhenchen ZHONG
,
Xiaokai SUN
,
Y.C. Chuang
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
110015
,
China
材料科学技术（英文）
In present investigation exchange interactions of Pr_(n+1)Co_(3n+5)B_(2n)-type compounds have been evalu- ated in the light of molecular-field theory. The exchange interactions and ferromagnetism in these compounds are discussed in terms of lattice parameters and interatomic distance between Co atom.
关键词:
Pr-Co-B alloy
,
null
,
null
张俊宝
,
雷延权
,
温广武
,
周玉
材料科学与工艺
doi:10.3969/j.issn.1005-0299.2003.03.002
为了制备氧化硅和氮化硼在分子甚至于原子级水平均匀混合的纳米级Si-B-O-N陶瓷粉体,利用溶胶-凝胶法合成了无碳型Si-B-O-N先驱体,通过先驱体热分解制备了Si-B-O-N陶瓷粉末,并利用DSC-TG、XRD、IR和TEM技术详细分析了Si-B-O-N先驱体凝胶的热分解特性和纳米粉体的组织结构与形貌特征.研究表明:先驱体凝胶的热分解主要发生在250～400℃,通过脱氨基原位聚合和无机化转变完成;Si-B-O-N陶瓷粉体呈非晶态,由均匀分布的B-N环、Si-O和Si-N-O等结构组成;粉末的形貌呈单一形态的球形颗粒,颗粒的平均粒径约为20 nm.
关键词:
Si-B-O-N陶瓷
,
先驱体
,
溶胶-凝胶法
,
纳米粉体
