Boron−nitrogen doped multiple resonance(BN-MR)emitters,characterized by B−N covalent bonds,offer distinctive advantages as pivotal building blocks for facile access to novel MR emitters featuring narrowband spectra an...Boron−nitrogen doped multiple resonance(BN-MR)emitters,characterized by B−N covalent bonds,offer distinctive advantages as pivotal building blocks for facile access to novel MR emitters featuring narrowband spectra and high efficiency.However,there remains a scarcity of exploration concerning synthetic methods and structural derivations to expand the library of novel BN-MR emitters.Herein,we present the synthesis of a BN-MR emitter,tCz[B−N]N,through a one-pot borylation reaction directed by the amine group,achieving an impressive yield of 94%.The emitter is decorated by incorporating two 3,6-di-tbutylcarbazole(tCz)units into a B−N covalent bond doped BN-MR parent molecule via para-C−π−D and para-N−π−D conjugations.This peripheral decoration strategy enhances the reverse intersystem crossing process and shifts the emission band towards the pure green region,peaking at 526 nm with a narrowband full-width at half maximum(FWHM)of 41 nm.Consequently,organic light emitting diodes(OLEDs)employing this emitter achieved a maximum external quantum efficiency(EQEmax)value of 27.7%,with minimal efficiency roll-off.Even at a practical luminance of 1000 cd·m^(−2),the device maintains a high EQE value of 24.6%.展开更多
Ab initio calculations of complexes formed between N-bromosuccinimide and a series of electron-donating groups were performed at the level of MP2/Lanl2DZ^＊ to gain a deeper insight into the nature of the N--Br haloge...Ab initio calculations of complexes formed between N-bromosuccinimide and a series of electron-donating groups were performed at the level of MP2/Lanl2DZ^＊ to gain a deeper insight into the nature of the N--Br halogen bonding. For the small complexes, H3 C--Br… NH3 and H2 N--Br…NH3 , the primary calculation has demonstrated that the N--Br in H2 N--Br… NH3 can form a much stronger halogen-bonding complex than the C--Br. A comparison of neutral hydrogen bond complex series reveals that the electron-donating capacities of the atoms decrease in the order, N 〉 O 〉 S; 0 （ sp^3 ） 〉 0 （ sp^2 ）, which is adequate for the C--Br halogen bonding. Interaction energies, in conjunction with the geometrical parameters show that the affinitive capacity of trihalide anions X^-3 with N-bromosuccinimide are markedly lower than that of the corresponding X^- with N-bromosuccinimide, even lower than those of neutral molecules with N-bromosueeinimide. AIM analyses further eorffirmed the above results.展开更多
The wettability and bonding in Ni/Ti(C, N) systems with multiple carbide additions were studied by sessile drop technique and vacuum brazing technique, respectively. The phase characterizations of substrates and fract...The wettability and bonding in Ni/Ti(C, N) systems with multiple carbide additions were studied by sessile drop technique and vacuum brazing technique, respectively. The phase characterizations of substrates and fracture surfaces were conducted by XRD. The microstructures at metal/ceramic interfaces and fracture surfaces were observed via SEM in back scattered mode and second electron mode, respectively. Furthermore, an X-ray energy-dispersive spectrometer (EDS) attached to SEM was used to study the elements diffusion in interfacial regions. The results reveal that diffusion and dissolution mechanism controlled reactive wetting takes place in the system in high temperature wetting. Results also show that the contact angles decrease with multiple carbide additions, and the effect of multiple carbide additions is stronger than that of single additions. The contact angle reaches the lowest value in the lowest TiC content case. The enhancement of the wettability is due to alloying procedure during high tempe展开更多
Developing high efficient Pd-based electrocatalysts for oxygen reduction reaction(ORR) is still challenging for alkaline membrane fuel cell,since the strong oxygen adsorption energy and easy agglomerative intrinsic pr...Developing high efficient Pd-based electrocatalysts for oxygen reduction reaction(ORR) is still challenging for alkaline membrane fuel cell,since the strong oxygen adsorption energy and easy agglomerative intrinsic properties. In order to simultaneously solve these problems, Pd/Co_(3)O_(4)–N–C multidimensional materials with porous structures is designed as the ORR catalysts. In details, the ZIF-67 with polyhedral structure was firstly synthesized and then annealed at high-temperature to prepare the N-doped Co_(3)O_(4)carbon-based material, which was used to homogeneously confine Pd nanoparticles and obtained the Pd/Co_(3)O_(4)–N–C series catalysts. The formation of Co–N and C–N bond could provide efficient active sites for ORR. Simultaneously, the strong electronic interaction in the interface between the Pd and N-doped Co_(3)O_(4)could disperse and avoid the agglomeration of Pd nanoparticles and ensure the exposure of active sites, which is crucial to lower the energy barrier toward ORR and substantially enhance the ORR kinetics. Hence, the Pd/Co_(3)O_(4)–N–C nanocompounds exhibited excellent ORR catalytic performance, ideal Pd mass activity, and durability in 0.1 mol L-1KOH solution compared with Co_(3)O_(4)–N–C and Pd/C. The scalable synthesis method, relatively low cost, and excellent electrochemical ORR performance indicated that the obtained Pd/Co_(3)O_(4)–N–C electrocatalyst had the potential for application on fuel cells.展开更多
The stable configurations and hydrogen bond nature of （H2O）n clusters （n = 3-6） have been investigated by the B3LYP method at the 6-31＋＋g^＊＊ level. Upon calculation, four conclusions have been drawn： （1） In...The stable configurations and hydrogen bond nature of （H2O）n clusters （n = 3-6） have been investigated by the B3LYP method at the 6-31＋＋g^＊＊ level. Upon calculation, four conclusions have been drawn： （1） In the （H2O）3-5 clusters, cyclic configurations were confirmed to be the most stable. But in the （H2O）3-4 ones, only cyclic configurations could be observed. From n = 5 （（H2O）5 clusters）, three-dimensional configuration could be found： （2） In the （H2O）6 clusters, all configurations are inclined to be three-dimensional except the most stable configuration which is cyclic; （3） The stable order of （H2O）6 clusters indicates that it is the arrangement of hydrogen bond that plays a decisive role in the cluster stabilities, the zero-point energy is also important, and cluster stabilities are independent on the number of hydrogen bonds; （4） There exist strong cooperativity and superadditivity in the （H2O）n clusters.展开更多
In order to investigate the tensile bond anchorage properties of Australian 500N steel bars in concrete, 111 pullout tests were conducted. The precise bond slip values have been gained by using the laser displacement ...In order to investigate the tensile bond anchorage properties of Australian 500N steel bars in concrete, 111 pullout tests were conducted. The precise bond slip values have been gained by using the laser displacement sensor with high resolution, including the complete bond-slip curves. How the main anchorage factors such as concrete strength, bar diameter （8, I0, 12, 16, 20, 24, 28, 32 and 36 mm） the concrete covered, embedded length and transverse reinforcement influencing the bond anchorage properties was studied under tensile condition. The process of the tensile force-slip failure for Australian 500N reinforcing steel can be divided into five stages： elastic stage, local slip stage, slip in ascent stage, slip in descent stage and remnant stage. The formula for calculating the tensile bond strength of Australian 500N reinforcing bar in concrete was proposed according to the test results, including the consistent model for tensile bond-slip relationship.展开更多
Based on ANSYS FEM software, the distribution of residual stress in the diffusion bonding joints between Ti（ C,N） metallic ceramic/interlayer/4OCr steel was calculated and experimentally ver^ed. The results showed t...Based on ANSYS FEM software, the distribution of residual stress in the diffusion bonding joints between Ti（ C,N） metallic ceramic/interlayer/4OCr steel was calculated and experimentally ver^ed. The results showed that the trend on the distribution of residual stress field in the joints was not changed with the use of interlayer. The maximum residual stress was always located in metallic ceramic with area ranging from 1 mm to 4 mm to the interlayer. The maximum residual stress in the joints was also affected by diffusion temperature. The satellite pulse current during the initial stage on diffusion bonding can promote the formation of liquid film at the interface, by which diffusion temperature and loading pressure can be greatly decreased. The crack initiation was easily produced at the corner of Ti （ C, N） metallic ceramic close to the interlayer. If a higher residual stress produced in the joints, the crack was propagated into the whole ceramic.展开更多
Solvothermal reactions of 4,4＇-oxybis（benzoic acid） （H2oba） with 1,3-dipyridyl benzene （1,3-dpb） produced a two-dimensional （2D） cadmium（Ⅱ） coordination polymer {[Cd（oba）（dpb）]·H2O}n （1）. The co...Solvothermal reactions of 4,4＇-oxybis（benzoic acid） （H2oba） with 1,3-dipyridyl benzene （1,3-dpb） produced a two-dimensional （2D） cadmium（Ⅱ） coordination polymer {[Cd（oba）（dpb）]·H2O}n （1）. The complex was characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. It crystallizes in the monoclinic system, space group C2/c with a = 13.6692（9）, b = 25.9647（17）, c = 8.7912（6） , α = 125.0370（10）, γ = 2544.7（3）°, V = 2544.7（3） 3, C30H22N2O6Cd, Mr = 618.91, Dc =1.609 g/cm3, F（000） = 1248, μ = 0.904 mm-1 and Z = 4. The neighboring Cd（Ⅱ） ions are linked by oba2-anions and 1,3-dpb to form an infinitely 2D wavelike sheet, and two such 2D sheets are interlocked with each other by H-bonding to form a 2D → 2D structure. The adjacent two groups of interlocked structures are further linked to form a bilayer 2D supramolecular network by π-π interactions. In addition, the fluorescence property of 1 was also studied.展开更多
Bonding of Si 3N 4 ceramic was performed with Y 2O 3 Al 2O 3 SiO 2(YAS) X glass solders,which were mixed with TiO 2 (YT) and Si 3N 4 (YN), respectively. The effects of bonding conditions and interfacial r...Bonding of Si 3N 4 ceramic was performed with Y 2O 3 Al 2O 3 SiO 2(YAS) X glass solders,which were mixed with TiO 2 (YT) and Si 3N 4 (YN), respectively. The effects of bonding conditions and interfacial reaction on the joint strength were studied. The joint strength in different bonding conditions was measured by four point bending tests. The interfacial microstructures were observed and analyzed by SEM, EPMA and XRD. It is shown that with the increase of bonding temperature and holding time, the joint strength increases reaching a peak, and then decreases. When TiO 2 is put into YAS solder,the bonding interface with Si 3N 4/(Y Sialon glass+TiN)/TiN/Y Sialon glass is formed. When YAS solder is mixed with Si 3N 4 powder, the interfacial residual thermal stress may be decreased, and then the joint strength is enhanced. According to microanalyses, the bonding strength is related to interfacial reaction.展开更多
Cardanol-aldehyde condensation polymer containing boron-nitrogen coordinate bond (CFBN) has been synthesized and characterized by IR, XPS, HPLC and DTA-TG. Its properties were also investigated. The results show tha...Cardanol-aldehyde condensation polymer containing boron-nitrogen coordinate bond (CFBN) has been synthesized and characterized by IR, XPS, HPLC and DTA-TG. Its properties were also investigated. The results show that the coating film of CFBN has excellent physico-mechanical properties, good anticorrosive properties and stable at high temperature. (Author abstract) 8 Refs.展开更多
Liquid bonding of Si 3N 4 ceramic composite was carried out with RE 2O 3 Al 2O 3 SiO 2 glass solders. The effect of bonding conditions and interfacial reaction on the joint strength was studied. The joint st...Liquid bonding of Si 3N 4 ceramic composite was carried out with RE 2O 3 Al 2O 3 SiO 2 glass solders. The effect of bonding conditions and interfacial reaction on the joint strength was studied. The joint strength under different bonding conditions was measured by four point bending tests. The interfacial microstructures were observed and analyzed by SEM, EPMA and XRD. It is shown that the liquid glass solders react with Si 3N 4 at interface, forming the Si 3N 4/Si 2N 2O/Y(La) sialon glass/Y(La) sialon glass gradient interface. With the increase of bonding temperature and holding time, the joint strength first increased reaching a peak, and then decreased. According to microanalyses, LaYO 3 precipitated from joint glass improves joint strength at room and high temperature.展开更多
Solid liquid state pressure bonding of Si 3N 4 ceramics with aluminum based alloys, which contain a small amount of intermetallic compounds Al 3Ti or Al 3Zr, was investigated. With this new method, the heat resistant ...Solid liquid state pressure bonding of Si 3N 4 ceramics with aluminum based alloys, which contain a small amount of intermetallic compounds Al 3Ti or Al 3Zr, was investigated. With this new method, the heat resistant properties of the bonding zone metal are improved, and the joints’ strengths at high temperature is increased. The joints’ shear strength at room temperature and at 600 ℃ reach 126～133 MPa and 32～34 MPa, respectively, with suitable bonding pressure. The reaction between aluminum and Si 3N 4 ceramics, which produces Al Si N O type compounds is the dominant interfacial reaction, while the reactions between the second active element Ti or Zr in the aluminum based alloys and Si 3N 4 ceramics also occur to some extend. [展开更多
Introduction There has been a very significarnt resurgence of interest in ab initio valence bond calculations recently. This is because the VB calculation based on nonorthogonal basis can provide intuitive understandi...Introduction There has been a very significarnt resurgence of interest in ab initio valence bond calculations recently. This is because the VB calculation based on nonorthogonal basis can provide intuitive understanding about many very important phenomena in chemistry. However, practical calculation based on nonorthogonal basis is still a great challenge even to deal with a quite small system due to the well-known N! (or展开更多
Urushiol polymer containing B-N bond (PUBN) was synthesized with urushiol-boron polymer and diethylene triamine. Its structure was characterized by XPS, IR, UV, HPLC, DTA-TG and elemental analysis. The physico-mechani...Urushiol polymer containing B-N bond (PUBN) was synthesized with urushiol-boron polymer and diethylene triamine. Its structure was characterized by XPS, IR, UV, HPLC, DTA-TG and elemental analysis. The physico-mechanical and anticorrosive properties of the polymer were also investigated. The results show that the coating of PUBN can be hardened in 2 h at room temperature and its film has excellent physico-mechanical properties and good anticorrosive properties.展开更多
The capacity factors （k＇） of fourteen types ofhalogenated thiophenols in different phases of methanol-water eluent were determined by reversed phased high-performance liquid chromatography （RP-HPLC） and the relat...The capacity factors （k＇） of fourteen types ofhalogenated thiophenols in different phases of methanol-water eluent were determined by reversed phased high-performance liquid chromatography （RP-HPLC） and the relationships between the logarithm of capacity factor lgK＇ and methanol ratio ψ were analyzed. A fair linear relationship is found between lgK＇ and ψ, and the correlation coefficients R2 of the constructed linear equations are all greater than 0.990. Relationship between the chromatographic data lgKw＇ when extrapolated to pure water and n-octanol/water partition coefficient lgKow obtained by the group contribution method has shown a good linear correlation with R2= 0.956. The structure parameters of fourteen halogenated thiophenols were calculated by using DFT, and the correlation equation of lgKw＇ and structure parameters was obtained by using SPSS, lgKw＇ = -0.409 ＋ 0.039a and R2 = 0.981, meaning that lgKw＇ is mainly determined by the polarizability α.展开更多
基金financial support from the National Natural Science Foundation of China(Nos.52303253 and 52273198)Yunnan Fundamental Research Project(No.202301BF070001-008)the Yunling Scholar Project of"Yunnan Revitalization Talent Support Program".
文摘Boron−nitrogen doped multiple resonance(BN-MR)emitters,characterized by B−N covalent bonds,offer distinctive advantages as pivotal building blocks for facile access to novel MR emitters featuring narrowband spectra and high efficiency.However,there remains a scarcity of exploration concerning synthetic methods and structural derivations to expand the library of novel BN-MR emitters.Herein,we present the synthesis of a BN-MR emitter,tCz[B−N]N,through a one-pot borylation reaction directed by the amine group,achieving an impressive yield of 94%.The emitter is decorated by incorporating two 3,6-di-tbutylcarbazole(tCz)units into a B−N covalent bond doped BN-MR parent molecule via para-C−π−D and para-N−π−D conjugations.This peripheral decoration strategy enhances the reverse intersystem crossing process and shifts the emission band towards the pure green region,peaking at 526 nm with a narrowband full-width at half maximum(FWHM)of 41 nm.Consequently,organic light emitting diodes(OLEDs)employing this emitter achieved a maximum external quantum efficiency(EQEmax)value of 27.7%,with minimal efficiency roll-off.Even at a practical luminance of 1000 cd·m^(−2),the device maintains a high EQE value of 24.6%.
基金Supported by the National Natural Science Foundation of China(No20502022)the Natural Science Foundation of Zhe-jiang Province(NoY406374)
文摘Ab initio calculations of complexes formed between N-bromosuccinimide and a series of electron-donating groups were performed at the level of MP2/Lanl2DZ^＊ to gain a deeper insight into the nature of the N--Br halogen bonding. For the small complexes, H3 C--Br… NH3 and H2 N--Br…NH3 , the primary calculation has demonstrated that the N--Br in H2 N--Br… NH3 can form a much stronger halogen-bonding complex than the C--Br. A comparison of neutral hydrogen bond complex series reveals that the electron-donating capacities of the atoms decrease in the order, N 〉 O 〉 S; 0 （ sp^3 ） 〉 0 （ sp^2 ）, which is adequate for the C--Br halogen bonding. Interaction energies, in conjunction with the geometrical parameters show that the affinitive capacity of trihalide anions X^-3 with N-bromosuccinimide are markedly lower than that of the corresponding X^- with N-bromosuccinimide, even lower than those of neutral molecules with N-bromosueeinimide. AIM analyses further eorffirmed the above results.
基金The authors wish to acknowledge the financial support from the National Natural Science Foundation of Chinathe Natural Science Foundation of Anhui Provincethe Project of Key Teachers of University of Education Ministry of China under contract No.50072003,No.03044902 and No.GG-805-10359-1840,respectively.
文摘The wettability and bonding in Ni/Ti(C, N) systems with multiple carbide additions were studied by sessile drop technique and vacuum brazing technique, respectively. The phase characterizations of substrates and fracture surfaces were conducted by XRD. The microstructures at metal/ceramic interfaces and fracture surfaces were observed via SEM in back scattered mode and second electron mode, respectively. Furthermore, an X-ray energy-dispersive spectrometer (EDS) attached to SEM was used to study the elements diffusion in interfacial regions. The results reveal that diffusion and dissolution mechanism controlled reactive wetting takes place in the system in high temperature wetting. Results also show that the contact angles decrease with multiple carbide additions, and the effect of multiple carbide additions is stronger than that of single additions. The contact angle reaches the lowest value in the lowest TiC content case. The enhancement of the wettability is due to alloying procedure during high tempe
基金funded by National Natural Science Foundation of China (21975129)Natural Science Foundation of Jiangsu Province (BK20190759)+1 种基金Nanjing Forestry UniversityPostgraduate Research & Practice Innovation Program of Jiangsu Province (SJCX21_0337)。
文摘Developing high efficient Pd-based electrocatalysts for oxygen reduction reaction(ORR) is still challenging for alkaline membrane fuel cell,since the strong oxygen adsorption energy and easy agglomerative intrinsic properties. In order to simultaneously solve these problems, Pd/Co_(3)O_(4)–N–C multidimensional materials with porous structures is designed as the ORR catalysts. In details, the ZIF-67 with polyhedral structure was firstly synthesized and then annealed at high-temperature to prepare the N-doped Co_(3)O_(4)carbon-based material, which was used to homogeneously confine Pd nanoparticles and obtained the Pd/Co_(3)O_(4)–N–C series catalysts. The formation of Co–N and C–N bond could provide efficient active sites for ORR. Simultaneously, the strong electronic interaction in the interface between the Pd and N-doped Co_(3)O_(4)could disperse and avoid the agglomeration of Pd nanoparticles and ensure the exposure of active sites, which is crucial to lower the energy barrier toward ORR and substantially enhance the ORR kinetics. Hence, the Pd/Co_(3)O_(4)–N–C nanocompounds exhibited excellent ORR catalytic performance, ideal Pd mass activity, and durability in 0.1 mol L-1KOH solution compared with Co_(3)O_(4)–N–C and Pd/C. The scalable synthesis method, relatively low cost, and excellent electrochemical ORR performance indicated that the obtained Pd/Co_(3)O_(4)–N–C electrocatalyst had the potential for application on fuel cells.
基金Project supported by the Natural Science Foundation of Tangshan Teacher’s College (No. 04C06)
文摘The stable configurations and hydrogen bond nature of （H2O）n clusters （n = 3-6） have been investigated by the B3LYP method at the 6-31＋＋g^＊＊ level. Upon calculation, four conclusions have been drawn： （1） In the （H2O）3-5 clusters, cyclic configurations were confirmed to be the most stable. But in the （H2O）3-4 ones, only cyclic configurations could be observed. From n = 5 （（H2O）5 clusters）, three-dimensional configuration could be found： （2） In the （H2O）6 clusters, all configurations are inclined to be three-dimensional except the most stable configuration which is cyclic; （3） The stable order of （H2O）6 clusters indicates that it is the arrangement of hydrogen bond that plays a decisive role in the cluster stabilities, the zero-point energy is also important, and cluster stabilities are independent on the number of hydrogen bonds; （4） There exist strong cooperativity and superadditivity in the （H2O）n clusters.
基金Project(DP0988940) supported by Australian Research Council Discovery Grant Program Project(2011M500930) supported by Postdoctoral Science Foundation of China+1 种基金Project(11KJB560003) supported by College Natural Science Foundation of Jiangsu Province,ChinaProject(163050072) supported by the Talent Introduction Foundation of Nanjing Forestry University,China
文摘In order to investigate the tensile bond anchorage properties of Australian 500N steel bars in concrete, 111 pullout tests were conducted. The precise bond slip values have been gained by using the laser displacement sensor with high resolution, including the complete bond-slip curves. How the main anchorage factors such as concrete strength, bar diameter （8, I0, 12, 16, 20, 24, 28, 32 and 36 mm） the concrete covered, embedded length and transverse reinforcement influencing the bond anchorage properties was studied under tensile condition. The process of the tensile force-slip failure for Australian 500N reinforcing steel can be divided into five stages： elastic stage, local slip stage, slip in ascent stage, slip in descent stage and remnant stage. The formula for calculating the tensile bond strength of Australian 500N reinforcing bar in concrete was proposed according to the test results, including the consistent model for tensile bond-slip relationship.
基金The authors are grateful to the financial support for this research from National Natural Science Foundation of China （Grant No. 51175259） , Jiangsu Science and Technology Planning Project （No. BK2011494） and University Science Research Project of Jiangsu Province （ 11KJAd30005 ）.
文摘Based on ANSYS FEM software, the distribution of residual stress in the diffusion bonding joints between Ti（ C,N） metallic ceramic/interlayer/4OCr steel was calculated and experimentally ver^ed. The results showed that the trend on the distribution of residual stress field in the joints was not changed with the use of interlayer. The maximum residual stress was always located in metallic ceramic with area ranging from 1 mm to 4 mm to the interlayer. The maximum residual stress in the joints was also affected by diffusion temperature. The satellite pulse current during the initial stage on diffusion bonding can promote the formation of liquid film at the interface, by which diffusion temperature and loading pressure can be greatly decreased. The crack initiation was easily produced at the corner of Ti （ C, N） metallic ceramic close to the interlayer. If a higher residual stress produced in the joints, the crack was propagated into the whole ceramic.
基金supported by the National Natural Science Foundation of China (21071004, 51173002)the Start-up Foundation and the young teacher’s research foundation of Anhui University of Science and Technology (11227, 2012QNZ08)the Research fund of Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province (AE 201107)
文摘Solvothermal reactions of 4,4＇-oxybis（benzoic acid） （H2oba） with 1,3-dipyridyl benzene （1,3-dpb） produced a two-dimensional （2D） cadmium（Ⅱ） coordination polymer {[Cd（oba）（dpb）]·H2O}n （1）. The complex was characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. It crystallizes in the monoclinic system, space group C2/c with a = 13.6692（9）, b = 25.9647（17）, c = 8.7912（6） , α = 125.0370（10）, γ = 2544.7（3）°, V = 2544.7（3） 3, C30H22N2O6Cd, Mr = 618.91, Dc =1.609 g/cm3, F（000） = 1248, μ = 0.904 mm-1 and Z = 4. The neighboring Cd（Ⅱ） ions are linked by oba2-anions and 1,3-dpb to form an infinitely 2D wavelike sheet, and two such 2D sheets are interlocked with each other by H-bonding to form a 2D → 2D structure. The adjacent two groups of interlocked structures are further linked to form a bilayer 2D supramolecular network by π-π interactions. In addition, the fluorescence property of 1 was also studied.
文摘Bonding of Si 3N 4 ceramic was performed with Y 2O 3 Al 2O 3 SiO 2(YAS) X glass solders,which were mixed with TiO 2 (YT) and Si 3N 4 (YN), respectively. The effects of bonding conditions and interfacial reaction on the joint strength were studied. The joint strength in different bonding conditions was measured by four point bending tests. The interfacial microstructures were observed and analyzed by SEM, EPMA and XRD. It is shown that with the increase of bonding temperature and holding time, the joint strength increases reaching a peak, and then decreases. When TiO 2 is put into YAS solder,the bonding interface with Si 3N 4/(Y Sialon glass+TiN)/TiN/Y Sialon glass is formed. When YAS solder is mixed with Si 3N 4 powder, the interfacial residual thermal stress may be decreased, and then the joint strength is enhanced. According to microanalyses, the bonding strength is related to interfacial reaction.
基金This work is supported by the National Science Foundation of China.
文摘Cardanol-aldehyde condensation polymer containing boron-nitrogen coordinate bond (CFBN) has been synthesized and characterized by IR, XPS, HPLC and DTA-TG. Its properties were also investigated. The results show that the coating film of CFBN has excellent physico-mechanical properties, good anticorrosive properties and stable at high temperature. (Author abstract) 8 Refs.
文摘Liquid bonding of Si 3N 4 ceramic composite was carried out with RE 2O 3 Al 2O 3 SiO 2 glass solders. The effect of bonding conditions and interfacial reaction on the joint strength was studied. The joint strength under different bonding conditions was measured by four point bending tests. The interfacial microstructures were observed and analyzed by SEM, EPMA and XRD. It is shown that the liquid glass solders react with Si 3N 4 at interface, forming the Si 3N 4/Si 2N 2O/Y(La) sialon glass/Y(La) sialon glass gradient interface. With the increase of bonding temperature and holding time, the joint strength first increased reaching a peak, and then decreased. According to microanalyses, LaYO 3 precipitated from joint glass improves joint strength at room and high temperature.
文摘Solid liquid state pressure bonding of Si 3N 4 ceramics with aluminum based alloys, which contain a small amount of intermetallic compounds Al 3Ti or Al 3Zr, was investigated. With this new method, the heat resistant properties of the bonding zone metal are improved, and the joints’ strengths at high temperature is increased. The joints’ shear strength at room temperature and at 600 ℃ reach 126～133 MPa and 32～34 MPa, respectively, with suitable bonding pressure. The reaction between aluminum and Si 3N 4 ceramics, which produces Al Si N O type compounds is the dominant interfacial reaction, while the reactions between the second active element Ti or Zr in the aluminum based alloys and Si 3N 4 ceramics also occur to some extend. [
文摘Introduction There has been a very significarnt resurgence of interest in ab initio valence bond calculations recently. This is because the VB calculation based on nonorthogonal basis can provide intuitive understanding about many very important phenomena in chemistry. However, practical calculation based on nonorthogonal basis is still a great challenge even to deal with a quite small system due to the well-known N! (or
基金This work is supported by the National Natural Science Foundation of China
文摘Urushiol polymer containing B-N bond (PUBN) was synthesized with urushiol-boron polymer and diethylene triamine. Its structure was characterized by XPS, IR, UV, HPLC, DTA-TG and elemental analysis. The physico-mechanical and anticorrosive properties of the polymer were also investigated. The results show that the coating of PUBN can be hardened in 2 h at room temperature and its film has excellent physico-mechanical properties and good anticorrosive properties.
文摘The capacity factors （k＇） of fourteen types ofhalogenated thiophenols in different phases of methanol-water eluent were determined by reversed phased high-performance liquid chromatography （RP-HPLC） and the relationships between the logarithm of capacity factor lgK＇ and methanol ratio ψ were analyzed. A fair linear relationship is found between lgK＇ and ψ, and the correlation coefficients R2 of the constructed linear equations are all greater than 0.990. Relationship between the chromatographic data lgKw＇ when extrapolated to pure water and n-octanol/water partition coefficient lgKow obtained by the group contribution method has shown a good linear correlation with R2= 0.956. The structure parameters of fourteen halogenated thiophenols were calculated by using DFT, and the correlation equation of lgKw＇ and structure parameters was obtained by using SPSS, lgKw＇ = -0.409 ＋ 0.039a and R2 = 0.981, meaning that lgKw＇ is mainly determined by the polarizability α.
