烧结循环水系统改进

从分析烧结工艺用水入手,介绍了烧结循环水系统的传统流程的构成和不足,通过改进流程的优点,环境效果和经济效果得到提升。并结合工程实例,介绍了该技术在新工程新项目中的推广。

烧结混合料加水的模糊自适应分数阶PI~λD^u控制

烧结混合料加水系统具有大滞后、模型复杂的特性,且客观环境中存在干扰因素,传统的控制方法很难取得理想的控制效果。分数阶PIλDu控制器比常规PID控制器多了两个可调参数,具有更好的控制效果。在分析分数阶微积分的基础上,给出了分数阶微积分的数字实现,用分数阶PIλDu控制代替常规PID控制,结合模糊控制,首次提出了一种针对烧结混合料加水系统的模糊自适应分数阶PIλDu控制方法,利用模糊逻辑实现分数阶PIλDu控制参数的在线调整。并用MATLAB/simulink进行建模仿真。仿真结果验证该控制算法的有效性,能取得较好的控制效果。

洗矿烧结洗涤混合水药法处理试验

我厂生产中每天约产生1.6万t洗矿、烧结、高炉煤气洗涤水,其中含,mg/L:悬浮物(SS)高达3158,铅44.2,锌57.1,严重污染资江的冷江段水域。为选择合理的处理方案、工艺设备、药剂及投药量,使上述有害物分别小于50、1、5mg/L,获得较好的经济效益和环境效益,进行了混合水处理试验,得到了一些结论,以供设计、生产参考。

嵌入式控制器在烧结配水系统中的应用

介绍了嵌入式系统在烧结配水系统中的应用,以烧结生产中的水分为控制对象,设计了一种基于S3C2410 ARM处理器和WINCE.Net操作系统的嵌入式控制器,并在其中嵌入了先进的无模型自适应控制算法。通过在烧结配水系统中的实际应用表明,相对传统的控制器,该控制器具有稳定性强、可靠性高、抗滞后能力强等特点。为工业控制领域中大滞后过程的控制提供了一种新的解决方案。

应用脉克星解决CAMI缸体水套芯烧结问题

我公司是一个以生产轿车和轻型车发动机汽缸体铸铁件为主的高度专业化铸造厂,年生产能力为100万件发动机缸体.CAMI缸体是为北美配套生产的车用V6发动机铸件,是典型的复杂薄壁铸件,主要壁厚为5mm±0.5mm,材质牌号相当于HT250,铸件质量70kg,浇注质量125kg,浇注温度为1410C-1430 C,浇注时间为14s-16s,砂芯由三乙胺冷芯盒法制成,浸涂COREFON水基涂料烘干,砂芯使用大林砂(50/100),三筛集中度82%,SiO2含量93%.

Hydrothermal synthesis, characterization and optical properties of La_2Sn_2O_7:Eu^(3+) micro-octahedra

Pyrochlore structure La2Sn2O7：Eu3＋ microcrystals with uniform octahedron shape were successfully synthesized via a hydrothermal route at 180 °C for 36 h. The crystal structure, particle size, morphologies, and optical properties of the as-synthesized products were investigated by XRD, TEM, SEM, EDS, FT-IR, Raman spectroscopy and PL. The effects of pH of precursor solution, precursor concentration, reaction temperature, and time were investigated. The results reveal that pH of the precursor solution not only plays an important role in determining the phase of the as-synthesized products, but also has a significant influence on the morphologies of the samples. High-quality and uniform octahedrons with an average size of about 700 nm could be easily obtained at the pH value of 12. The possible formation mechanism of octahedral-like La2Sn2O7：Eu3＋ microcrystals was briefly proposed. The photoluminescence spectra show that La2Sn2O7：Eu3＋ micro-octahedra display stronger emission in the range of 582-592 nm compared with the samples with other shapes.

Sintering microstructure and properties of copper powder prepared by electrolyzation and atomization

The almost completely dense copper was prepared by ultrafine copper powder prepared with both methods of electrolysis and novel water-gas atomization through cold isostatic pressing(CIP)and sintering under atmospheric hydrogen.Fine copper powder possesses the higher sintering driving force,thereby promoting shrinkage and densification during the sintering process.The grain size of sintered samples by electrolytic copper powder is smaller than that prepared by the atomized copper powder,and the twin crystals are particularly prone to forming in the former sintered microstructure due to the raw powder with low oxygen content and high residual stress originating from the CIP process.The relative density of samples by electrolytic and atomized powder at 1000℃ sintering temperature achieves 99.3%and 97.4%,respectively,significantly higher than that of the powder metallurgy copper parts reported in the literature.Correspondingly,the ultimate tensile strength and yield strength of samples by both kinds of copper powder are approximately similar,while the elongation of the sintered sample by the electrolytic powder(60%)is apparently higher than the atomized powder(44%).The superior performance of samples fabricated by electrolytic powder is inferred from the full density and low oxygen level for there is no cuprous oxide in the grain boundaries.

Physical and combustion properties of briquettes from sawdust of Azadirachta indica

The study was undertaken to investigate the properties of cassava starch and gum arabic bonded briquettes from the sawdust of Azadirachta indica. The briquettes were produced using a Jack press at an average pressure of 10.7 kg.cm^-2. The sawdust and binders were mixed at ratios of 100：15, 100：25, 100：35 and 100：45 in weight, respec tively. The briquettes produced were subjected to physical and combustion tests. Both the physical and combustion properties of the briquettes vary with binder types and binder levels （p 〈 0.05）. The result shows that briquettes bonded with starch gave better performance based on density of 0.546 g.cm^-3, durability rating of 95.93%, heating value of 33.09 MJ.kg^-1, percentage of fixed carbon of 84.70% and low ash and volatile matter of 3.35% and 11.95%, respectively, while briquette bonded with gum arabic has density of 0.425 g.cm^-3, durability rating of 94.85%, heating value of 32.76 MJ.kg^-l, percentage of fixed carbon of 87.30% and low ash and volatile matter of 4.45% and 8.75, respectively. Since the aim of briquetting is to produce briquette that will serve as a good source of fuel and support combustion, the best briquette was produced when the sawdust-starch ratio and sawdust-gum arabic ratio was 100：25 and 100：35, respectively.

Fabrication of superhydrophilic surface on copper substrate by electrochemical deposition and sintering process

Superhydrophilic surfaces were fabricated on copper substrates by an electrochemical deposition and sintering process. Superhydrophobic surfaces were prepared by constructing micro/nano-structure on copper substrates through an electrochemical deposition method. Conversion from superhydrophobic to superhydrophilic was obtained via a suitable sintering process. After reduction sintering, the contact angle of the superhydrophilic surfaces changed from 155° to 0°. The scanning electron microscope （SEM） images show that the morphology of superhydrophobic and superhydrophilic surfaces looks like corals and cells respectively. The chemical composition and crystal structure of these surfaces were examined using energy dispersive spectrometry （EDS） and X-ray diffraction （XRD）. The results show that the main components on superhydrophobic surfaces are Cu, Cu2O and CuO, while the superhydrophilic surfaces are composed of Cu merely. The crystal structure is more inerratic and the grain size becomes bigger after the sintering. The interracial strength of the superhydrophilic surfaces was investigated, showing that the interfacial strength between superhydrophilic layer and copper substrate is considerably high.

Key parameters for low temperature warm compaction of high density iron-based P/M materials

In order to reduce powder temperature to lower than 100℃ in warm compaction by changing polymer lubricant design, powder flowability, warm compacting behavior, lubricating mode as well as ultimate tensile strength after sinter-hardening and tempering were investigated systematically. By means of low temperature warm pressing and sintered hardening technique, samples with the sintered densities of 7.407.45g/cm3 and the strengths of 950 1390MPa are achieved as the early compacting pressure is 686735MPa.

Three-dimensional simulation of sintering crunodes of metal powders or fibers by level set method

The difference of sintering crunodes of metal powders and fibers is discussed. The mathematical model of the surface diffusion described by the difference in mean curvature is defined as a Hamilton-Jacobi-type equation, and the model is numerically solved by the level set method. The three-dimensional numerical simulations of two metal powders and fibers(the fiber angle is 0° or 90°) are implemented by this mathematical model, respectively. The numerical simulation results accord with the experimental ones. The sintering neck growth trends of metal powders and metal fibers are similar. The sintering neck radius of metal fibers is larger than that of metal powders. The difference of the neck radius is caused by the difference of geometric structure which makes an important influence on the curvature affecting the migration rate of atoms.

Super-High Heat Flux Removal Using Sintered Metal Porous Media

Heat transfer experiments using various porous materials are performed to verify the possibility of extremely high heat flux removal （several dozens of MW/m^2）. The porous media introduced in this experiment are bronze particle-sintered ones and copper fibers-sintered ones that have high thermal conductivity, each of which can enhance the thermal diffusion in the porous material. From the heat transfer experiments using a non-transferred type of plasma arcjet as a high heat flux source, the steady heat removal of 66.0 MV~/m2 is proved by using the bronze porous medium whose pore size and porosity are 100 μm and 0.38, respectively. Furthermore, as the result of evaluating the heat removal performance for various copper fiber porous media with the porosity from 0.5 to 0.7 and the fiber diameter from 30 to 90 μm, it is clarified that the maximum cooling performance exceeds 70.0 MW/m^2 at the porosity of 0.7 and the fiber diameter of 90μm, and that using the lower porosity material is useful for improving an evaporation rate in the porous media.

A simple approach to porous low-temperature-sintering BaTiO_3

Porous tetragonal BaTiO 3 ceramic was successfully prepared by a combination of hydrothermal and low-temperature-sintering method.The hollow TiO2@BaCO 3 as the sintering precursor was synthesized via a simple hydrothermal method,and then porous BaTiO 3 was generated by calcining the hollow TiO2@BaCO 3 precursor at 900 ℃ without additive.The hollow TiO2@BaCO 3 structure plays two important roles in the preparing of the porous BaTiO 3 ceramic.First,the TiO2@BaCO 3 hollow structure provides high surface areas and increases the contact points between BaCO 3 and TiO2,which can reduce the sintering temperature of the BaTiO 3 ceramic.Second,the cavity of the ordered arranged TiO2@BaCO 3 hollow sphere shows important influence on the porous structure,and the pore size of the as-prepared porous BaTiO 3 ceramic can be tuned from several nanometers to hundreds nanomters by changing the sintering temperature.The formation mechanism of the porous BaTiO 3 ceramic was proposed.

A new sediment type of coated grain: Oolitic sinter

As a special sedimentary grain type, the coated grain(with an ooid model) has been known for two centuries due to its fascinating special fabric and genesis developments. The leading factors in forming the coated grain consist mainly of:(1) microorganism movement field;(2) chemical sedimentary effect;(3) hydrodynamic force environment and topography condition;(4) abundant core material supply;(5) embedding condition; and(6) humic acids condition in water medium. With the development of the coated grain genesis, the single factor theory cannot reasonably explain the exact formation of the surface sediment of coated grain. Here, we find a new way to study the coated grain on the basis of traditional research methods. The Wenquan area on the northeast edge of the Qiangtang Basin is one of the few areas where the coated grain is developing, and is a rare "natural laboratory" for the study of the coated grain and the thermal spring sediment. The oolitic sinter of the area has the triaxiality modality of pea polymer, and is obviously different from the karst travertine and the normal lacustrine ooid. We found that the hot spring water in the Wenquan area has higher partial pressure of CO2(PCO2) and saturation index of the calcite(SIc) than normal. Macrocosmically, the oolitic sinter is shaped like a pea, and its grains and gap fillings are light yellow. Microcosmically, the sinter grain forms six types of fundamental lamina, and those six types are developed to be four grain types with different combinations. The C-axis of the mineral grain of sinter cement(calcite) is normal to the lamina face, and grows on it with distinct generation formations. In short, the grain type of oolitic sinter is the oncoid, with the grain development caused by the factors such as the shallow water of strong hydrodynamic force, the special hydrochemistry condition, and the extensive algae activities(diatom).