Ti3SiC2/TiB2 composite was successfully obtained by hot pressing Ti/TiC/Si/B4C power *** fraction of TiB2 in Ti3SiC2/TiB2 composite can not exceed 10%.Incorporation of excessive TiB2 will affect the reactions *** and ...
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Ti3SiC2/TiB2 composite was successfully obtained by hot pressing Ti/TiC/Si/B4C power *** fraction of TiB2 in Ti3SiC2/TiB2 composite can not exceed 10%.Incorporation of excessive TiB2 will affect the reactions *** and Ti5Si3 were two important intermediate phases during the whole *** microstructure characteristics of the Ti3SiC2/TiB2 composites were analyzed using scanning electron microscopy （SEM） and transmission electron microscopy （TEM）.The experimental results show that the grains of Ti3SiC2/TiB2 composite are structured in a layered form,and the formation of TiB2 particles as reinforcements with elongated or equiaxed shape distributes in Ti3SiC2 matrix.
It is very difficult to prepare full-densified aluminum nitride-boron nitride(AIN/BN)composite ceramics with homogeneous microstructure and high thermal *** plasma sintering(SPS)was used to fully densify the AIN/BN co...
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It is very difficult to prepare full-densified aluminum nitride-boron nitride(AIN/BN)composite ceramics with homogeneous microstructure and high thermal *** plasma sintering(SPS)was used to fully densify the AIN/BN composites in this ***,mechanical properties and thermal conductivity of the SPS sintered AIN/BN composites with 5-30 vol% BN were *** results show that the microstructure of composites is fine and homogenous,and the AIN/BN composites exhibit high mechanical *** promote the growth of AIN grains and modify the distribution of grain boundary in AIN/BN composites,a heat treating methodology was introduced through gas pressure sintering(GPS).This processing was significantly beneficial to enhancing the thermal conductivity of the *** thermal conductivity of AIN/BN composites with 5-30 vol% BN reached 60 W/m K after the samples were treated by GPS.
The etch damage in integrated ferroelectric capacitors side wall fabricated by the typical integrated process （TIP- FeCAP） and the innovated integrated process （IIP-FeCAP） are investigated by piezoresponse force m...
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The etch damage in integrated ferroelectric capacitors side wall fabricated by the typical integrated process （TIP- FeCAP） and the innovated integrated process （IIP-FeCAP） are investigated by piezoresponse force microscopy （PFM）. The IIP-FeCAP side wall exhibits fine and dear nanoscale domain images and the same piezoresponse signal as the thin film, and the domains can also be easily switched by an external voltage. In the TIP-FeCAP side wall, owing to the effect of etch damage, the very weak piezoresponse signal and some discrete domains can be observed, and the discrete domains cannot be switched by the applied 9 V and -9 V dc voltage. The PFM results reflect the etch damage in the integrated ferroelectric capacitors and also suggest that the PFM can be used as an efficacious tools to evaluate the etch damage at nanoscale and spatial variations.
Hydroxyapatite whiskers are used as reinforcement for biomaterials because of their needlelike morphology and strong strength of single crystal. HAP nanoparitcles are used in drug delivery system, protein separation a...
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Hydroxyapatite whiskers are used as reinforcement for biomaterials because of their needlelike morphology and strong strength of single crystal. HAP nanoparitcles are used in drug delivery system, protein separation and anticancer drug besides their implant applications. Many new properties arise from nanoeffects while nanoeffects come from specialty of nanostructure. The Ca（NO3）2·4H2O and （NH4）2HPO4 were used as starting reagents for preparation of HAP whiskers and nanoparticles. The whiskers are 100-200 μm long while nanoparticles are 30-80 nm in size. XRD is applied to characterize the lattice parameter difference of whisker and nanoparticle. Compared with those of HAP whiskers, the a-axis and b-axis of HAP nanocrystals are shortened while the c-axis is elongated. That makes nanoparticles capable of their non-needle-like morphology, higher reaction activity and special bioeffects.
Microwave boriding layer microstructure of carbon steels and its diffusion mechanics were studied. The results show that the existence of microwave field in the boriding can＇t change the growth mechanics of boriding ...
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Microwave boriding layer microstructure of carbon steels and its diffusion mechanics were studied. The results show that the existence of microwave field in the boriding can＇t change the growth mechanics of boriding layer. Compared with conventional boriding, if the treatment temperature and time remain constantly, the descend rate of the boriding layer thickness with the increase of carbon content of steel is smaller. The diffusion activation energy ofT8 steel is 2.6× 10^5 J/mol between the temperature of 750 ℃ and 900 ℃ in microwave field, which is in the same order of conventional boriding.
The morphology, mechanical properties of unsaturated polyester（UP） resin modified with TDI were studied via dynamic FT-1R spectra, SEM, DMA and mechanical property testing. Results show that companying with the cure...
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The morphology, mechanical properties of unsaturated polyester（UP） resin modified with TDI were studied via dynamic FT-1R spectra, SEM, DMA and mechanical property testing. Results show that companying with the cured cross-linking reaction of UP resin, TDI can firstly react with UP and produce polyurethane（PU）, and then UP and PU form the cross-linking nets together. The impact fracture section morphology of modified UP resin manifested the typical sea- islands structure. Testing of mechanical properties showes that for introducing of PU, the TDI has an obvious effect on the toughness and strength of UP resin. When the ratio of TDI/UP （w/w） was 7.5%, the modified UP resin exhibited the best mechanical properties with flexural strength of 125 MPa, impact strength of 18 kJ·m^-2 and tensile strength of 72 MPa.
W-15Cu composite powders prepared by mechanical alloying （MA） of raw powders were consolidated by spark plasma sintering （SPS） process at temperature ranged 1 230-1 300 ℃ for 10 min and under a pressure of 30 MPa...
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W-15Cu composite powders prepared by mechanical alloying （MA） of raw powders were consolidated by spark plasma sintering （SPS） process at temperature ranged 1 230-1 300 ℃ for 10 min and under a pressure of 30 MPa. By using high energy milling, particles containing very fine tungsten grains embedded in copper, called composite particles, could be produced. The W grains were homogeneously dispersed in copper phase, which was very important to obtain W-Cu alloy with high mechanical properties, fine and homogeneous microstructure. The microstructure and properties of W-15Cu alloys prepared by SPS processes at different temperature were researched. The results show that W-15Cu alloys consolidated by SPS can reach 99.6 % relative density, and transverse rupture strength （TRS） is 1 400.9 MPa, Rockwell C hardness （HRC） is 45.2, the thermal conductivity is 196 W/m-K at room temperature, the average grain size is less than 2 μm, and W-15Cu alloy with excellent properties, homogeneous and fine microstructure is obtained.
The influences of mass concentration of nickel chloride hexahydrate, sodium borohydride, ethylenediamine, pH value, bath temperature on deposition rate were studied with orthogonal experiments by a series of pre-treat...
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The influences of mass concentration of nickel chloride hexahydrate, sodium borohydride, ethylenediamine, pH value, bath temperature on deposition rate were studied with orthogonal experiments by a series of pre-treatments on micro-diamond particle, and the optimized parameters were obtained. Both the morphology and the composition of original diamond and the diamond with Ni-B coating were analyzed by SEM and XRD respectively. The SEM image shows that the spherical Ni-B particle is coated upon diamond. XRD pattern shows that the coating compositions are Ni and Ni2B.
With industrial grade Al（OH）3 as raw materials, the self dispersion nanosized AlOOH crystal powder were prepared by the sol-hydrothermal method. The results of XRD and TEM show that the nanosized AlOOH could automat...
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With industrial grade Al（OH）3 as raw materials, the self dispersion nanosized AlOOH crystal powder were prepared by the sol-hydrothermal method. The results of XRD and TEM show that the nanosized AlOOH could automatically disperse to a single-dispersing state in water without surface modification, dispersant, additive and accessional conditions （ultrasonic wave dispersing, ball-mill dispersing）. The application results of the product indicate that the nanosized AlOOH can be composed into a toughened nanocomposites without surface modification. Accordingly, the self dispersion characteristic and mechanism of hydrothermal crystallization and charging composite dispersion of nanosized AIOOH are found, and a new technique of preparing polymer/inorganic nanocomposites is proposed, which is called blending compositing new techniques of sol even dispersing at auasi-homogeneous phase.
The influence of different relative density on the cyclic oxidation behaviors of MoSi2 at 1 273 K were studied. ＂Pesting＂ was not found in all MoSi2 materials after being oxidized for 480 h. All samples exhibited co...
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The influence of different relative density on the cyclic oxidation behaviors of MoSi2 at 1 273 K were studied. ＂Pesting＂ was not found in all MoSi2 materials after being oxidized for 480 h. All samples exhibited continuous mass gain during the oxidation process. The mass gains of MoSi2 with the lowest relative density （78.6%） and the highest relative density （94.8%） are increased by 8.15 mg·cm^-2 and 3.48 mg·cm^-2, respectively. The surface of the material with lower relative density formed a loose, porous and discontinuous oxidation scale, which accelerated oxygen diffusion and aggravated the oxidation process. However, a dense scale in the material with higher relative density is formed, which acts a diffusion barrier to the oxygen atoms penetrating into the matrix. The high temperature oxidation resistance of MoSi2 can be improved by increasing its relative density.
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