氯化亚锡对阻燃体系复合酚醛泡沫性能的影响

以多聚磷酸铵、季戊四醇、氯化亚锡为原料组成膨胀型阻燃系统,研究氯化亚锡添加量对膨胀型阻燃系统复合酚醛泡沫的极限氧指数、燃烧热量释放速率、燃烧总热释放量、有效燃烧热量、耗氧量、烟气释放、有毒气体释放等的影响。研究结果表明阻燃体系复合泡沫的极限氧指数在72.8%~74.5%之间,展现出良好的阻燃性,阻燃体系对酚醛泡沫的阻燃符合气相阻燃的机理,并且在氯化亚锡添加量为1.5%时,阻燃体系复合泡沫的阻燃性能最优。     

邻苯二甲腈树脂复合材料阻燃低毒特性研究

从热释放速率、毒性、有害气体浓度、氧指数、烟密度、水平和垂直燃烧性能等方面系统地研究了邻苯二甲腈树脂复合材料的阻燃低毒特性。在辅射强度为50kW／m^2时,邻苯甲腈复合材料的热释放速率为21kW／m^2,点燃时间为500s。同时其氧指数大于70％,烟密度小于20,表明邻苯二甲腈树脂复合材料是一种理想的阻燃低毒复合材料。     

炭化处理对重组竹阻燃抑烟性能影响

利用锥形量热仪、氧指数测定仪和烟密度测定仪研究了炭化处理对重组竹阻燃抑烟性能的影响,结果表明,炭化处理可以降低重组竹燃烧热释放速率和质量损失速率,减少热释放总量,增大氧指数,延迟点燃时间。炭化处理使重组竹燃烧热释放速率峰值降低了36.6%、达到峰值的时间延迟了450s,点燃时间增加了5倍,氧指数增大了49.3%,质量损失速率峰值降低了21.8%、达到峰值的时间延迟了505s;炭化处理显著降低了重组竹烟生成速率、烟生成总量、烟密度及一氧化碳与二氧化碳释放速率。炭化处理使重组竹燃烧烟密度降低了35.9%,一氧化碳与二氧化碳释放速率达到最大值时间延迟了600s左右。炭化处理对重组竹具有明显的阻燃抑烟效果。     

环保型硅胶泡沫阻燃抑烟及热分解特性EI北大核心CSCD

以铂(Pt)为催化剂,采用脱氢法制备了环保阻燃硅胶泡沫(SiFs),通过锥形量热仪测试方法分析其火灾危险性,并利用极限氧指数、烟密度和热分析等手段研究了催化剂Pt及阻燃剂超细氢氧化铝(ATH)、超细碳酸钙(CC)、超细氢氧化镁(MDH)和氢氧化铝/碳酸钙(ATH/CC)对SiFs阻燃抑烟和热分解特性的影响。研究结果表明,SiFs的火灾安全性优于聚氨酯(PU)和聚甲基丙烯酸甲酯(PMMA)材料。Pt含量对SiFs的阻燃及热分解特性影响显著,当Pt的质量分数为0.6%和0.9%时,SiFs的阻燃抑烟性能较好。Pt质量分数为0.9%时,SiF的初始分解温度最高,热稳定性好。阻燃剂添加量越多,阻燃效果越好,添加ATH的SiFs阻燃性能最好。ATH和MDH具有优异的抑烟性能,但添加ATH和MDH的SiFs力学性能随添加量增加而下降。此外,Pt及阻燃填料能够影响SiFs的初始热解温度,减缓热分解进程。     

环保型硅胶泡沫阻燃抑烟及热分解特性

以铂(Pt)为催化剂,采用脱氢法制备了环保阻燃硅胶泡沫(SiFs),通过锥形量热仪测试方法分析其火灾危险性,并利用极限氧指数、烟密度和热分析等手段研究了催化剂Pt及阻燃剂超细氢氧化铝(ATH)、超细碳酸钙(CC)、超细氢氧化镁(MDH)和氢氧化铝/碳酸钙(ATH/CC)对SiFs阻燃抑烟和热分解特性的影响。研究结果表明,SiFs的火灾安全性优于聚氨酯(PU)和聚甲基丙烯酸甲酯(PMMA)材料。Pt含量对SiFs的阻燃及热分解特性影响显著,当Pt的质量分数为0.6%和0.9%时,SiFs的阻燃抑烟性能较好。Pt质量分数为0.9%时,SiF的初始分解温度最高,热稳定性好。阻燃剂添加量越多,阻燃效果越好,添加ATH的SiFs阻燃性能最好。ATH和MDH具有优异的抑烟性能,但添加ATH和MDH的SiFs力学性能随添加量增加而下降。此外,Pt及阻燃填料能够影响SiFs的初始热解温度,减缓热分解进程。     

PP/PVAc-OMMT纳米复合材料及其阻燃材料的燃烧性能

利用锥形量热仪(CONE)在35kW/m2热辐照条件下,并结合极限氧指数(LOI)和UL-94垂直燃烧测试方法对聚丙烯(PP)/聚醋酸乙烯酯(PVAc)-有机蒙脱土(OMMT)纳米复合材料和加入无卤复配阻燃剂制备的PP/PVAc-OMMT/氢氧化镁(MH)/三氧化二锑(AO)纳米复合阻燃材料的热释放速率、烟释放及材料在燃烧时的质量损失行为进行了研究。结果表明,添加10%(质量分数)PVAc-OMMT可以提高PP材料的阻燃性能,燃烧时的热释放速率、质量损失率以及烟释放量减少,且PVAc-OMMT与无卤复配阻燃剂之间可产生阻燃协效作用,使纳米复合阻燃材料的阻燃性能、热稳定性和抑烟性进一步增强。     

2,4,6-三溴苯胺阻燃聚甲基丙烯酰亚胺泡沫的制备及性能

通过自由基共聚合和热空气自由发泡两步法,制备阻燃聚甲基丙烯酰亚胺(PMI)泡沫,其中功能单体为甲基丙烯酸(MAA)和丙烯腈(AN)、阻燃剂为2,4,6-三溴苯胺(TBA)、引发剂为偶氮二异丁腈(AIBN)、发泡剂为甲酰胺(FA)。通过泡沫垂直燃烧和极限氧指数(LOI)研究了PMI泡沫的阻燃性能,通过锥形量热仪研究了PMI泡沫的燃烧行为,通过热重分析研究了PMI泡沫的热降解性能,通过扫描电镜对PMI泡沫的形貌进行表征,同时对阻燃PMI泡沫的拉伸、弯曲和压缩强度进行测试。结果表明,当添加8 phr TBA时,PMI50/8TBA泡沫燃烧的火焰高度明显降低,LOI高达26.3%;同时,峰值热释放速率和总热释放量相对于PMI50分别下降了25.5%,41.6%。TBA的加入,使得阻燃PMI泡沫泡孔壁变薄,从而降低了材料力学强度。     

二维层状无机物/硼酸锌复合体系对聚苯乙烯泡沫阻燃性能的影响

通过三聚氰胺改性脲醛树脂包覆的方法来制备阻燃聚苯乙烯泡沫(EPS),阻燃体系以聚磷酸铵为基础,并选用3种二维层状无机物和硼酸锌的复配体系作为协效剂,对比了不同阻燃体系对聚苯乙烯泡沫的阻燃、抑烟和热稳定性的影响。实验结果表明:当膨胀石墨与硼酸锌的添加量为2∶1(质量比),两者总添加量为24phr时,复合材料的极限氧指数可达32.6%,UL-94垂直燃烧测试达V-0等级,烟密度等级降低至27.31;较之添加纯膨胀石墨EPS样品,协效剂硼酸锌的引入,使样品残炭强度由14.3增加到86.1。热失重分析结果表明,协效剂的加入使得样品热稳定性和残炭率均有所上升。从残炭宏观形貌和扫描电镜结果可以看出,硼酸锌的存在,使样品燃烧后残炭更加完整、致密,裂痕与破损明显减少。     

二丙基次磷酸铝对尼龙6的阻燃作用

通过极限氧指数测定、垂直燃烧实验和锥型量热分析研究了二丙基次磷酸铝(ADPP)对尼龙6(PA6)的阻燃作用。结果表明,ADPP对PA6具有良好的阻燃效果。当ADPP添加量为15%时,阻燃PA6的LOI就高达30.7%,阻燃等级达V-0。与未阻燃PA6相比,燃烧时的热释放速率和质量损失速率显著降低,但累计热释放量略有增大。热重和残余物分析结果表明,ADPP是通过气相和凝聚相同时产生阻燃作用的。一方面它通过分解成不挥发性磷酸铝和促进PA6成炭,形成膨胀层而产生阻燃作用;另一方面,它分解成挥发性磷化物,在气相通过捕获燃烧产生的自由基而抑制燃烧。ADPP热稳定性良好,能满足聚酰胺的加工要求,但其使用明显降低了PA6的热稳定性。     

磷改性膨胀石墨对硬质聚氨酯泡沫燃烧性能的影响

用六氯环三磷腈(HCCP)对可膨胀石墨(EG)进行改性,所得改性可膨胀石墨(EGP)用于硬质聚氨酯泡沫(RPUF)的阻燃处理。利用红外光谱、热重分析和扫描电镜表征EGP的结构特征。利用万能试验机、极限氧指数(LOI)和锥形量热(CONE)研究了EGP对RPUF力学性能和阻燃性能的影响,通过扫描电镜和热重分析研究了RPUF样品燃烧后残炭的微观形貌和阻燃机理。分析结果表明,随着EG或EGP添加量的增加其LOI随之增加,在相同添加量的情况下RPUF/EGP的LOI最高,且其力学性能优于RPUF/EG的力学性能;由于EGP促使RPUF分解产生更加致密坚固的炭层,所以RPUF/EGP的点燃时间比RPUF/EG推迟了4s,其热释放速率峰值、总的热释放量、烟释放速率峰值和总的烟释放量分别比RPUF/EG降低了9.1%、5.9%、19.0%和33.8%,EGP表现出优于EG的阻燃抑烟性能。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.     

The Influence of Nitrogen and Boron Implant into Silicon Substrate on the Phase and Internal Stress of c-BN Films

Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously.