一体化膨胀型防火涂料的热解机理研究

为解决传统防火涂料的装饰性问题,设计并合成了一种一体化膨胀型防火涂料.采用热红联用技术对该防火涂料的热解行为进行了研究,发现其热解过程可以分为4个阶段:第1阶段后期,炭化反应开始;第2阶段不稳定磷酸酯结构的断裂释放出CO2等气体,使熔融炭化物发生初步膨胀;第3阶段气体产物使炭化层进一步膨胀,最后硬化形成多孔炭化层;最终阶段炭化层高温热解.研究发现该防火涂料的热解反应发生顺序符合膨胀防火体系的要求,可以顺利地形成具有多孔结构的炭化层来保护基材.     

TG-FTIR study on urea-formaldehyde resin residue during pyrolysis and combustion

The pyrolysis and combustion characteristics of urea-formaldehyde resin (UFR) residue were investigated by using thermogravimetric analysis, coupled with Fourier transform infrared spectroscopy (TG-FTIR). It is indicated that the pyrolysis process can be subdivided into three stages: drying the sample, fast thermal decomposition and further cracking process. The total weight loss of 90 wt.% at 950 °C is found in pyrolysis, while 74 wt.% of the original mass lost in the second stage is between 195 °C and 430 °C. The emissions of carbon dioxide, isocyanic acid, ammonia, hydrocyanic acid and carbon monoxide are identified in UFR residue pyrolysis, moreover, isocyanic acid emitted at low temperature is found as the most important nitrogen-containing gaseous product in UFR residue pyrolysis, and there is a large amount of hydrocyanic acid emitted at high temperature. The similar TG and emission characteristics as the first two stages during pyrolysis are found in UFR residue combustion at low temperature. The combustion process almost finishes at 600 °C; moreover, carbon dioxide and water are identified as the main gaseous products at high temperature. It is indicated that the UFR residue should be pyrolyzed at low temperature to remove the initial nitrogen, and the gaseous products during pyrolysis should be burnt in high temperature furnace under oxygen-rich conditions for pollutant controlling.     

A study concerning the decomposition of vitroplastic material during differentiated carbon burnout

The quasisteady decomposition of a vitroplastic material is analyzed in the case of carbon burnout both in the inner layers and at the surface.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 24, No. 4, pp. 601–607, April, 1973.     

Study of the degradation of power generation combustion components at elevated temperature

Elevated temperature combustion of fuel oil that contains large amounts of vanadium, asphaltenes and mostly sulfur, presents a major challenge for materials selection and design of combustion components for the electric power generation. The combustion system, which consists of air nozzles and air swirlers, plays a key role in the performance of electric power plants. Air nozzles and air swirlers, which were operated for one year in a 350 MW boiler, were analyzed, presenting accelerated degradation. The particular features of corrosion behavior of these components made by stainless steels: 304, 446 and HH, are presented. The results obtained after optical, metallographic, and microprobe analysis revealed that the components flame contact at very high operating temperature promoted all materials degradation mechanisms. Under this scenario, it is very difficult to find a material resistant to such accelerated wastage conditions. So, the solution of the problem must be oriented to re-design and improve the efficiency of the flame contact with these components.     

Development of a thermal barrier material using combustion synthesis

The present investigation employs combustion synthesis as a method to produce a functionally graded Ni₃Al/Al₂O₃+TiB₂ composite material for use as a thermal barrier system for nickel-based alloys at elevated temperatures. Starting materials were Ni, Al, TiO₂ and B₂O₃ in powder form. Adiabatic thermodynamic calculations used to determine the maximum theoretical temperature reached during combustion suggest that up to 1600 K may be reached in the Ni+Al metallic layer, easily sufficient to initiate the ceramic-based reaction. The latter reaction is predicted to reach 3000 K. Experiments were first conducted in an induction furnace to establish conditions necessary for combustion to occur. Subsequent experimentation, with applied pressure during combustion, was conducted in a Gleeble 1500 thermomechanical test unit modified to accept the samples of interest. Characterisation of the combustion products by means of hardness measurements, X-ray diffraction, scanning electron microscopy and electron probe microanalysis confirmed that the products were Ni₃Al and Al₂O₃+TiB₂. Also, the mechanical integrity was unchanged after 10 thermal cycles in the modified Gleeble unit. Finally, the coating thickness required to keep a Ni-based substrate below 850°C in a 1100°C environment is estimated to be 1.8 mm, based on thermal conductivity calculations using a finite element method.     

Applications of nonlinear ultrasonics to the NDE of material degradation

Nonlinear ultrasonics is suggested as a new approach for the effective evaluation of material degradation. As its quantification, the parameter beta is introduced on the basis of nonlinear elasticity, and a new method to measure the parameter beta using bispectral analysis is proposed. Then, the correlation between beta and material degradation is investigated. From the results for several mild steel (SS41, SS45) specimens that were degraded by stretching and cyclic loads, it was confirmed that the parameter beta has a strong correlation with material degradation. As another practical application, the evaluation of the aging degradation in a high temperature material is tried. For this, Cr-Mo-V specimens that are generally used in turbine rotors in power plants were prepared, and the variation of beta caused by aging time was investigated. For comparison, the fracture appearance transition temperature (FATT) of the specimen was measured, and its behavior showed good agreement with beta. In addition, for all of the experiments, no noticeable change in attenuation and sound velocity in the same specimens with change of degradation were observed. From these results, it may be concluded that nonlinear ultrasonics could be applied to the quantitative evaluation of material degradation.     

可控降解抗感染材料的合成和表征

在聚己内酯(PCL)与六亚甲基二异氰酸酯(HDI)缩合体系中加入抗菌药物环丙沙星(CF),制备CF嵌入聚氨酯(PU)主链的聚氨酯前药CFPU。用UV、FTIR、H-NMR表征其结构;GPC法测定分子量;UV法测定载药率;摸索影响其分子量和载药率的主要因素;并用琼脂稀释法测定其胆固醇酯酶(CE)降解液对金黄色葡萄球菌的抗菌活性。结果表明,确已成功制得目标产物;PCL浓度和HDI加料方式分别对其平均分子量和载药率有较大影响;而其CE降解液对金黄色葡萄球菌具有抗菌活性。因此,当其用作医用内植物的涂层材料时,能被炎症组织所分泌的CE可控降解为这种具抗菌活性的降解液,从而可发挥抗感染作用。     

Determination of the thermal state of material subjected to erosive degradation

The experimental data are generalized and governing parameters and analytic relations for estimating the thermal state of material subjected to the thermoerosive action of a dusty gas flow are proposed. Comparison of the results of numerical calculations obtained using the method described in [1] with estimates based on the relations proposed gives the error of the latter.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 52, No. 2, pp. 209–215, February, 1987.     

改善发射药燃烧性能的包覆物选择研究

采用树脂及乳液对发射药表面进行包覆,改善发射药的燃烧性能,比较不同包覆层对燃烧性能的影响.结果表明,包覆层种类的差异对于发射药的燃烧温度影响不大;丙烯酸和苯丙乳液适于作为包覆原料,其包覆层能起到较好调节燃速的作用.     

Variation in the heat exchange of combustion products over an oscillation period during vibrational flame propagation

The heat fluxes from the combustion products to the pipe walls as a function of time are determined. Experiments confirm the physical mechanism suggested in the report for the variation in heat exchange over an oscillation period during vibrational flame propagation.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 34, No. 5, pp. 885–888, May, 1978.     

Heat and mass exchange in combustion of a liquid combustible material in a room with an open aperture

An integrated mathematical model of heat and mass exchange for fire in a room that has open apertures is suggested. The results of numerical investigation are presented for the effect of the fundamental parameters of the problem on the mean volumetric parameters of the gaseous atmosphere of the room, the temperatures of the enclosing structures, and on the parameters of the natural gas exchange with the environment through an open aperture in the case of combustion of a liquid combustible material.     

Identification of the combustion front of an oil resevoir

A method is proposed for determining the rate of movement of the combustion zone in an oil resevoir from temperature perturbations of the earth's surface layer.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 56, No. 3, pp. 373–378, March, 1989.     

Some principles of combustion of homogeneous fuel-air mixtures in the cylinder of an internal combustion engine

An algorithm is presented for the problem of flame propagation rate in combustion of a homogeneous fuel-air mixture in the cylinder of an internal combustion engine. It is assumed that the mixture is not overturbulized and that the flame front is spherical. The model used for the phenomenon is based on a turbulent transport mechanism. In the near-wall region the combustion mechanism follows a fine-scale mechanism, but in the core, a large-scale mechanism.Experiments permitted determination of the character and numerical value of coefficients which consider the effect of turbulence on flame front propagation in the combustion chamber of a ZMZ-4021 engine.The principles presented can be used as the basis of an algorithm for heat liberation rate in an internal combustion engine with external mixture formation.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 59, No. 6, pp. 942–947, December, 1990.     

Mechanism of coal combustion in a fluidized layer of coarsely dispersed material

A system of one-dimensional steady-state balance equations is formulated for fuel, oxidizer, and energy. An approximate solution is obtained and compared to experiments on coal combustion in a fluidized layer.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 50, No. 2, pp. 260–266, February, 1986.     

典型硼化合物对毛竹热降解与燃烧性能的影响

利用热重和锥形量热仪研究硼酸、硼砂两种典型硼化合物对毛竹热降解和燃烧性能的影响。结果表明:硼酸、硼砂能降低竹材的最大热解速率,缩短高温热解区间,促进残炭生成。与未处理材相比,硼酸、硼砂明显减少竹材燃烧过程中的热量释放,热释放速率降至未处理材的50%左右,总热释放量的降幅分别达50.6%、44.1%。硼酸、硼砂也能抑制竹材燃烧时的烟释放,总烟释放量分别下降95.3%、91.6%。硼酸、硼砂处理竹材能发挥高效的阻燃抑烟功效。     

Sepiolite as a deodorant material: an ESR study of its properties

Sepiolite, a Mg silicate, is used as a deodorant because of its strong adsorbing power. However, the principle by which sepiolite adsorbs gases is not known well. The present authors have tried to analyse this principle as a change of paramagnetic species in the crystal surfaces of sepiolite. After heat-processing sepiolite at the temperatures 150, 550 and 750C, the concentration change of paramagnetic species was observed using NH₃, air, or vacuum as atmospheric environment of sepiolite. The results indicate that, in the absence of zeolitic water, relatively high concentrations of Mn²⁺ and (Mg²⁺) _n ^– (are observed, which are destroyed with NH₃ or water. A multi-line ESR spectrum has been found and is attributed to (Mg²⁺) _n ^– ion which is an entire crystal lattice plane forming a big molecular orbital. The results and an analysis of it seem to indicate that a gas molecule is adsorbed to a crystal plane of sepiolite due to its free spin holding nature. This phenomenon may be called spin adsorption. There should be many more cases in which gas adsorption from the gas phase to the solid phase is controlled by the free-spin holding nature of the solid surface. For such cases the ESR method seems to be a quite powerful and proper technique.     

Modeling of the material behavior during hot hydroforming

For the purpose of numerically simulating metal forming processes, material data are necessary, determined by testing procedures similar to the particular process. The new technology of hot tube bulge tests has been introduced recently, fulfilling the requirements of material data determination for hot hydroforming. Based on measurement data gained by this technology, selected constitutive relations for approximating the flow stress depending on temperature, strain rate and logarithmic strain were parameterized applying linear regression analysis. Using the material law with the best approximation quality among the regarded equations, a numerical simulation of an exemplary forming process was accomplished. A comparison between the experimentally obtained geometry after a hot hydroforming process and the prediction by numerical analysis is used for evaluating the quality and applicability of the determined material data for this kind of process. Additionally, a process simulation, using extrapolated material data from compression tests is presented to visualize the influence of the testing procedure on the resulting part geometry prediction.