A series of 2-methylenesuccinimides modified by germatranes were synthesized br two methods. The structures of products were confirmed by (1)HNMR, IR elemental analysis, and X-ray diffraction.
A new approach to the massive production of TiC whiskers with high purity and low cost was presented. It is a modified carbothermal reduction method （MCTR） characterized by argon stream flowing vertically and passin...A new approach to the massive production of TiC whiskers with high purity and low cost was presented. It is a modified carbothermal reduction method （MCTR） characterized by argon stream flowing vertically and passing through the interior of the mixture of raw materials. It is found for the first time that there is an optimum flow of the upward flowing argon stream, at which large quantity of high quality TiC can be obtained. This paper described the new method, analyzed the mechanism and conditions for the formation of high purity TiC whiskers on a large scale, and compared MCTR with the traditional carbothermal reduction method （TCTR）. Based on the analysis and comparison, it is concluded that in order to produce high quality transition metal carbides, nitrides and carbonitrides with low cost TCTR must be replaced by MCTR.展开更多
In this paper we reported the preparation and extensive characterization of La9.83–x Sr x Si6O26＋δ（0≤x≤0.50） precursors, intermediate and final products. The sintering reactions, the phase formation, the struct...In this paper we reported the preparation and extensive characterization of La9.83–x Sr x Si6O26＋δ（0≤x≤0.50） precursors, intermediate and final products. The sintering reactions, the phase formation, the structure as well as the powders＇ morphology were studied by means of thermogravimetric analysis, X-ray diffraction（XRD）, Fourier-transform infrared spectroscopy（FTIR） and scanning electron microscopy（SEM）. Moreover, the effect of stoichiometry on precursor＇s structure and morphology as well as on intermediate and final products was reported. As was concluded pure La9.83Si6O26＋δ, La9.38Sr0.45Si6O26＋δ and La9.33Sr0.50Si6O26＋δ could be prepared after sintering at 1400 °C for 20 h while La9.68Sr0.15Si6O26＋δ and La9.53Sr0.30Si6O26＋δ compounds contained minor traces（〈3.5%） of La2Si2O7 secondary phase. Concerning the synthesis, there have been no previous reports on the preparation of pure La9.83Si6O26＋δ, La9.38Sr0.45Si6O26＋δ and La9.33Sr0.50Si6O26＋δ compounds. The final powders consisted of spherical particles and an increase of Sr content seemed to inhibit sintering phenomena. The existence of interstitial oxygen at intermediate crystallographic positions of apatite structure had great effect on Si O4 sub-structure distortion. The increase of Sr content led to a major reduction of interstitial oxygen quantity and the refutation of silicon tetrahedron distortion.展开更多
文摘A series of 2-methylenesuccinimides modified by germatranes were synthesized br two methods. The structures of products were confirmed by (1)HNMR, IR elemental analysis, and X-ray diffraction.
文摘A new approach to the massive production of TiC whiskers with high purity and low cost was presented. It is a modified carbothermal reduction method （MCTR） characterized by argon stream flowing vertically and passing through the interior of the mixture of raw materials. It is found for the first time that there is an optimum flow of the upward flowing argon stream, at which large quantity of high quality TiC can be obtained. This paper described the new method, analyzed the mechanism and conditions for the formation of high purity TiC whiskers on a large scale, and compared MCTR with the traditional carbothermal reduction method （TCTR）. Based on the analysis and comparison, it is concluded that in order to produce high quality transition metal carbides, nitrides and carbonitrides with low cost TCTR must be replaced by MCTR.
基金funded by the Research Committee of National Technical University of Athens
文摘In this paper we reported the preparation and extensive characterization of La9.83–x Sr x Si6O26＋δ（0≤x≤0.50） precursors, intermediate and final products. The sintering reactions, the phase formation, the structure as well as the powders＇ morphology were studied by means of thermogravimetric analysis, X-ray diffraction（XRD）, Fourier-transform infrared spectroscopy（FTIR） and scanning electron microscopy（SEM）. Moreover, the effect of stoichiometry on precursor＇s structure and morphology as well as on intermediate and final products was reported. As was concluded pure La9.83Si6O26＋δ, La9.38Sr0.45Si6O26＋δ and La9.33Sr0.50Si6O26＋δ could be prepared after sintering at 1400 °C for 20 h while La9.68Sr0.15Si6O26＋δ and La9.53Sr0.30Si6O26＋δ compounds contained minor traces（〈3.5%） of La2Si2O7 secondary phase. Concerning the synthesis, there have been no previous reports on the preparation of pure La9.83Si6O26＋δ, La9.38Sr0.45Si6O26＋δ and La9.33Sr0.50Si6O26＋δ compounds. The final powders consisted of spherical particles and an increase of Sr content seemed to inhibit sintering phenomena. The existence of interstitial oxygen at intermediate crystallographic positions of apatite structure had great effect on Si O4 sub-structure distortion. The increase of Sr content led to a major reduction of interstitial oxygen quantity and the refutation of silicon tetrahedron distortion.
