Effect of fluidity on the manufacturing of open cell magnesium alloy foams

The effect of fluidity on open cell AZ31 metal foam samples fabricated using a solid state space holder method was investigated.Granule was fabricated by plaster powder and perlite powder.Granules were sieved which compacted layer by layer in casting mold.Preforms which made by granules were then heated to 200℃,300℃,400℃,500℃ under a rough(mechanical)vacuum before pressure infiltration with AZ31 Mg alloy.Samples were infiltrated using vacuum pressure values range of 8-14 KPa.The conditions of pressure and temperature were performed in order to get different fluidity on manufacturer of open cell AZ31 metal foam specimen quantity.It is found that the fluidity plays significant role to determine the open cell AZ31 alloy foam.The fluidity is affected by preheat temperature and infiltration vacuum pressure.The macrostructure,the distribution of the pores,microstructure,infiltration length,and porosity were investigated.

Heat Transfer and Acoustic Properties of Open Cell Aluminum Foams

The aluminum open cell foams have been prepared by the conventional precision casting method to investigate the thermal and acoustic properties.A water heating system and silencers were organized as a first step for its applications.The temperature increase between the top and bottom of the foam became larger as the cell size increased in the heat transfer measurement.Sound absorption ratio of the close cell foams was 60%-100%, whereas the open cell aluminum foam showed only 10%-20% of sound absorption at low frequency.When the prototype electric water heater manufactured by combining aluminum open cell foam with a heater was heated to 100-400℃,the highest temperature of water was in the range of 16-46~C.This suggests that there could be potential for this type of heater to be used as a commercial electric water heater.Sound silencer made with the aluminum open cell foam was applied to exit of exhaustion side at air pressure line.Sound silencing effect of open-celled aluminum foam showed that the noise level went down by introducing smaller cell size foam.

TFT-LCD open cell制程

文章主要介绍TFT-LCD open cell制程,TFT-LCD open cell制程一般分为前段、中段和后段制程,前段制程主要是进行TFT玻璃的制作;中段制程主要指将TFT玻璃与彩色滤光片贴合;后段制程指驱动IC、印刷电路板和液晶板的压合。

Electro-Deposition of Cu on Open Cell Aluminum Foams

This manuscript deals with the electro-deposition of Cu on aluminum foams. Metallic foams are highly porous materials which present complex structure of three-dimensional open cells. This aspect causes strong limitations in mass transport due to electro-deposition technology. Experimental tests were performed to study the influence of the operational parameters on the overall performance of the coated aluminum foams. The experimental findings revealed that the manufactured metal foams were characterized by a high thermal conductivity and low process costs, making these materials very promising in many technological fields. On the basis of the experimental results, analytical models are proposed to predict the quantity and the quality characteristics of the coating.

Modeling and Simulation of Heterojunction Solar Cell with Mono Crystalline Silicon

The monocrystalline silicon is a promising material that could be used in solar cells that convert light into electricity. Although the cost of ordinary silicon (Si) solar cells has decreased significantly over the past two decades, the conversion efficiency of these cells has remained relatively high. While solar cells have a great potential as a device of renewable energy, the high cost they incur per Watt continues to be a significant barrier to their widespread implementation. As a consequence, it is vital to conduct research into alternate materials that may be used in the construction of solar cells. The heterojunction solar cell (HJSC), which is based on n-type zinc oxide (n-ZnO) and p-type silicon (p-Si), is one of the numerous alternatives of the typical Si single homojunction solar cell. There are many deficiencies that can be found in the published research on n-ZnO/p-Si heterojunction solar cell. Inconsistencies in the stated value of open circuit voltage (Voc) of the solar cell are one example of deficiency. The absence of a full theoretical study to evaluate the potential of the solar cell structure is another deficiency that can be found in these researches. A lower value of experimentally obtained VOC in comparison to the theoretical prediction based on the band-gap between n-ZnO and p-Si. There needs to be more consensus among scientists regarding the optimal conditions for the growth of zinc oxide. Many software’s are available for simulating and optimizing the solar cells based on these parameters. For this purpose, in this dissertation, I provide computational results relevant to n-ZnO/p-Si HJSC to overcome deficiencies that have been identified. While modeling and simulating the potential of the solar cell structure with AFORS-HET, it is essential to consider the constraints that exist in the real world. AFORS-HET was explicitly designed to mimic the multilayer solar cell arrangement. In AFORS-HET, we can add up to seven layers for solar cell layout. By using this software, we can figure out the open circuit voltage (VOC), the short circuit current (JSC), the quantum efficiency (QE, %), the heterojunction energy band structure, and the power conversion efficiency (PCE).

Numerical Modeling of the Compression Process of Elastic Open-cell Foams

The random models of open-cell foams that can reflect the actual cell geometrical properties are constructed with the Voronoi technique. The compression process of elastic open-cell foams is simulated with the nonlinear calculation module of finite element analysis program. In order to get the general results applicable to this kind of materials, the dimensionless compressive stress is used and the stress-strain curves of foam models with different geometrical properties are obtained. Then, the influences of open-cell geometrical properties, including the shape of strut cross section, relative density and cell shape irregularity, on the compressive nonlinear mechani- cal performance are analyzed. In addition, the numerical results are compared with the predicted results of cubic staggering model. Nu- merical results indicate that the simulated results reflect the compressive process of foams quite well and the geometrical properties of cell have significant influences on the nonlinear mechanical behavior of foams.

Thermal properties of open-celled aluminum foams prepared by two infiltration casting methods

Contrastive research was carried out to study the thermal properties of open-celled aluminum foams prepared by counter-gravity infiltration casting system and the traditional process respectively.The experimental results show that the thermal conductivity coefficients of aluminum foams prepared by two different infiltration methods have similar increasing trend with the increase of particle size;along with the reducing porosity,the thermal conductivity coefficients will be enhanced oppositely.However,with the same particle size,the open-celled aluminum foam prepared by the former method has a higher thermal conductivity coefficient obviously.It is largely because that the sample prepared by counter-gravity infiltration casting has a lower void content and better dense crystallization of metal-matrix after the constant pressure process.

Analysis and simulation for tensile behavior of anisotropic open-cell elastic foams

Based on the elongated Kelvin obtained to investigate the tensile behavior Kelvin model＇s periodicity and symmetry in model, a simplified periodic structural cell is of anisotropic open-cell elastic foams due to the whole space. The half-strut element and elastic deflection theory are used to analyze the tensile response as done in the previous studies. This study produces theoretical expressions for the tensile stress-strain curve in the rise and transverse directions. In addition, the theoretical results are examined with finite element simulation using an existing formula. The results indicate that the theoretical analysis agrees with the finite element simulation when the strain is not too high, and the present model is better. At the same time, the anisotropy ratio has a significant effect on the mechanical properties of foams. As the anisotropy ratio increases, the tensile stress is improved in the rising direction but drops in the transverse direction under the same strain.

Preparation of open-cell metal foams by investment cast

Metal foams are a new kind of materials with low densities and novel physical, mechanical, thermal, electrical and acoustic properties. They can be divided into closed and open cell structures. In this paper the open cell structures, called sponges, were treated. A new technique to manufacture sponges by plaster investment casting was described. Experimental results show that it is essential to make a sound plaster mould by casting plaster slurry into the polyurethane foams and infiltrate the open channels of the baked plaster mold by molten metal. The optimal processes include plaster slurry preparation, plaster mold baking, and molten metal infiltration. The sponge sample with porosity of 97% is presented.

Effects of microstructure on uniaxial strength asymmetry of open-cell foams

Based on the elongated Kelvin model, the effect of microstructure on the uniaxial strength asymmetry of open-cell foams is investigated. The results indicate that this asymmetry depends on the relative density, the solid material, the cell morphology, and the strut geometry of open-cell foams. Even though the solid material has the same tensile and compressive strength, the tensile and compressive strength of open-cell foams with asymmetrical sectional struts are still different. In addition, with the increasing degree of anisotropy, the uniaxial strength as well as the strength asymmetry increases in the rise direction but reduces in the transverse direction. Moreover, the plastic collapse ratio between two directions is verified to depend mainly on the cell morphology. The predicted results are compared with Gibson and Ashby＇s theoretical results as well as the experimental data reported in the literature, which validates that the elongated Kelvin model is accurate in explaining the strength asymmetry presented in realistic open-cell foams.

Preparation and properties of open-cell zinc foams as human bone substitute material

Foamed zinc was prepared by infiltration casting process.The mechanical properties and corrosion resistance of the samples were studied,and the feasibility of the foamed zinc as a bone implant material was discussed.All the compression stress-strain curves of open-cell zinc foams with various cell size(1-4 mm)and porosity(55%-67%)show three stages:elastic stage,plastic stage,and densification stage.The compression strength increases with decreasing density.The smooth stress-strain response indicates a progressively deformation of open-cell zinc foam.In addition,the cell wall or edge bending and fracture are the dominated mechanisms for failure of open cell zinc foam.The immersion test for determining the corrosion rate of open cell zinc foam was conducted in simulated body fluid.It was found that zinc foam with a small cell size and high porosity showed a higher corrosion rate.In addition,open-cell zinc foams can effectively induce Ca-P deposition in immersion tests,showing good bioactivity.Therefore,the open cell zinc foam prepared in this experiment has a good potential application as a human bone substitute material.

Improvement of the Open Circuit Voltage of CZTSe Thin-Film Solar Cells by Surface Sulfurization Using SnS

The objective of this study is to find an effective method to improve Voc without Jsc loss for Cu2ZnSnSe4 （CZTSe） thin film solar cells, which have been fabricated by the one step co-evaporation technique. Surface sulfurization of CZTSe thin films is carried out by using one technique that does not utilize toxic H2S gas; a sequential evaporation of SnS after CZTSe deposition and the annealing of CZTSe thin films in selenium vapor. A Cu2ZnSn（S, Se）4 （CZTSSe） thin layer is grown on the surface of the CZTSe thin film after the annealing. The conversion efficiency of the completed device is improved due to the enhancement of Voc, which could be attributed to the formation of a hole-recombination barrier at the surface or the passivation of the surface and grain boundary by S incorporation.

Open-circuit voltage analysis of p-i-n type amorphous silicon solar cells deposited at low temperature

This paper identifies the contributions of p-a-SiC：H layers and i-a-Si：H layers to the open circuit voltage of p-i-n type a-Si：H solar cells deposited at a low temperature of 125℃. We find that poor quality p-a-SiC：H films under regular conditions lead to a restriction of open circuit voltage although the band gap of the i-layer varies widely. A significant improvement in open circuit voltage has been obtained by using high quality p-~SiC：H films optimized at the ＂low-power regime＂ under low silane flow rates and high hydrogen dilution conditions.

An analytical model to explore open-circuit voltage of a-Si:H/c-Si heterojunction solar cells

The effect of the parameters on the open-circuit voltage, V_(OC) of a-Si:H/c-Si heterojunction solar cells was explored by an analytical model. The analytical results show that V_(OC) increases linearly with the logarithm of illumination intensity under usual illumination. There are two critical values of the interface state density(D_(it)) for the open-circuit voltage(V_(OC)), D_(it)^(crit,1) and D_(it)crit,2(a few 1010 cm^(-2)·e V^(-1)). V_(OC) decreases remarkably when D_(it) is higher than D_(it)^(crit,1). To achieve high V_(OC), the interface states should reduce down to a few 1010 cm^(-2)·e V^(-1). Due to the difference between the effective density of states in the conduction and valence band edges of c-Si, the open-circuit voltage of a-Si:H/c-Si heterojunction cells fabricated on n-type c-Si wafers is about 22 mV higher than that fabricated on p-type c-Si wafers at the same case. V_(OC) decreases with decreasing the a-Si:H doping concentration at low doping level since the electric field over the c-Si depletion region is reduced at low doping level. Therefore, the a-Si:H layer should be doped higher than a critical value of 5×10^(18) cm^(-3) to achieve high V_(OC).

Comparisons of ganglion cell-inner plexiform layer loss patterns and its diagnostic performance between normal tension glaucoma and primary open angle glaucoma: a detailed, severity-based study

AIM: To evaluate the patterns of macular ganglion cell-inner plexiform layer(GCIPL) loss in normal tension glaucoma(NTG) and primary open angle glaucoma(POAG) in a detailed, disease severity-matched way;and to assess the diagnostic capabilities of GCIPL thickness parameters in discriminating NTG or POAG from normal subjects.METHODS: A total of 157 eyes of 157 subjects, including 57 normal eyes, 51 eyes with POAG and 49 eyes with NTG were enrolled and strictly matched in age, refraction, and disease severity between POAG and NTG groups. The average, minimum, superotemporal, superior, superonasal, inferonasal, inferior, and inferotemporal GCIPL thickness, and the average, superior, temporal, inferior, and nasal retinal nerve fiber layer(RNFL) thickness were obtained by Cirrus optical coherence tomography(OCT). The diagnostic capabilities of OCT parameters were assessed by area under receiver operating characteristic(AUROC) curves. RESULTS: Among all the OCT thickness parameters, no statistical significant difference between NTG group and POAG group was found(all P>0.05). In discriminating NTG or POAG from normal subjects, the average and inferior RNFL thickness, and the minimum GCIPL thickness had better diagnostic capabilities. There was no significant difference in AUROC curve between the best GCIPL thickness parameter(minimum GCIPL) and the best RNFL thickness parameter in discriminating NTG(inferior RNFL;P=0.076) and indiscriminating POAG(average RNFL;P=0.913) from normal eyes.CONCLUSION: Localized GCIPL loss, especially in the inferior and inferotemporal sectors, is more common in NTG than in POAG. Among all the GCIPL thickness parameters, the minimum GCIPL thickness has the best diagnostic performance in differentiating NTG or POAG from normal subjects, which is comparable to that of the average and inferior RNFL thickness.

稳定“海岛”结构诱导高强度PS/PPO开孔泡沫制备与性能研究

采用熔融共混法制备了聚苯乙烯(PS)/聚苯醚(PPO)共混材料。通过控制加工温度,使得PPO以刚性粒子形式存在于共混物中,形成稳定“海岛”结构。以超临界CO_(2)为发泡剂进行了釜压发泡,得到了高开孔率的PS开孔泡沫。研究了PPO含量对PS流变性能、热力学行为的影响以及稳定“海岛”结构对形成PS开孔泡沫的影响,对所得PS/PPO泡沫制品的泡孔尺寸、发泡倍率、开孔率及泡沫压缩性能进行了分析。结果表明,当发泡温度为158℃、压力为20 MPa、PPO含量为10份(质量份,下同)时,可以制备得到发泡倍率为37.5倍、开孔率为96.9%的PS开孔泡沫。

开孔泡沫金属传热和流动特性

近年来开孔泡沫金属运用于散热设备逐渐成为研究的热点。由于开孔泡沫金属结构复杂无序,数值模拟时大都将其结构进行化简,目前已有种类繁多的简化模型,然而适用于其传热与流动特性模拟研究的简化模型尚不明确;另外,适用于散热领域的泡沫金属结构参数有待详细研究。为此,建立开孔泡沫金属的5种简化三维模型,并进行传热和流动特性的对比研究,认为Gibson-Ashby模型更能准确描述实际开孔泡沫金属的传热和流动性能。在此基础上,采用Gibson-Ashby模型对开孔泡沫金属的关键结构参数进行传热和流动综合性能分析,发现孔隙率90%、孔密度30PPI开孔泡沫金属翅片的综合性能j/f^(1/3)(j为换热因子,f为阻力因子)最优;将孔隙率90%、孔密度30PPI开孔泡沫金属翅片与平直翅片进行对比,发现开孔泡沫金属翅片换热效果是平直翅片的2倍以上,综合性能也优于平直翅片。所得研究成果可为开孔泡沫金属在换热领域的应用和设计提供参考。

抗氧化小分子体掺杂对锡铅钙钛矿太阳电池性能的影响

锡铅钙钛矿中存在各种缺陷,且Sn^(2+)容易被氧化成Sn^(4+),从而导致太阳电池的转换效率和稳定性较差。研究发现4-香豆酸(p-C)的引入可显著改变薄膜的表面形貌、有效提高结晶性,且抑制Sn^(2+)的氧化,有利于提高钙钛矿层与传输层之间的能级匹配度。通过对钙钛矿光吸收层的缺陷进行钝化,可显著提升太阳电池的光电特性。最终,锡铅钙钛矿太阳电池的开路电压提升65mV,光电转换效率由18.14%提升至20.37%,并且电池稳定性得到显著提升。

废弃聚氨酯硬泡的回收再利用研究

以废弃聚氨酯硬泡为原料,研究了降解条件对降解效果的影响以及降解产物对开孔型聚氨酯硬泡性能的影响。具体考察了醇解剂、胺解剂、催化剂对硬泡溶解能力和产物特性的影响,以及再生多元醇的羟值、用量对泡沫开孔率和尺寸稳定性等的影响。结果表明:使用固体酸催化并采用先醇解后胺解的方式可有效降解板材废泡,降解所得再生多元醇的羟值为550~800 mgKOH/g,用量占组合聚醚质量分数的10%~40%时,可获得性能优良的开孔型聚氨酯硬泡。

开孔剂对慢回弹聚氨酯泡沫开孔性的影响及检测方法对比研究

将开孔剂KY1216、BDM-5、1900H以不同用量应用于慢回弹聚氨酯泡沫配方中,采用传统吐泡法(TBM)、透气仪法(BM)、塌泡落差法(BCDM)对不同试样的开孔效果进行检测。结果表明,采用BCDM检测泡沫开孔性能时数据直观、判断准确、方便快捷,成本低,提高了开孔剂的检测效率,值得作为慢回弹开孔剂的高效检测方法推广和应用。