Optimization of chemistry and process parameters for control of intermetallic formation in Mg sludges

Intermetallic formation in sludge during magnesium(Mg)melting,holding and high pressure die casting practices is a very important issue.But,very often it is overlooked by academia,original equipment manufacturers(OEM),metal ingot producers and even die casters.The aim of this study was to minimize the intermetallic formation in Mg sludge via the optimization of the chemistry and process parameters.The Al8Mn5 intermetallic particles were identified by the microstructure analysis based on the Al and Mn ratio.The design of experiment(DOE)technique,Taguchi method,was employed to minimize the intermetallic formation in the sludge of Mg alloys with various chemical compositions of Al,Mn,Fe,and different process parameters,holding temperature and holding time.The sludge yield(SY)and intermetallic size(IS)was selected as two responses.The optimum combination of the levels in terms of minimizing the intermetallic formation were 9 wt.%Al,0.15 wt.%Mn,0.001 wt.%(10 ppm)Fe,690℃ for the holding temperature and holding at 30 mins for the holding time,respectively.The best combination for smallest intermetallic size were 9 wt.%Al,0.15 wt.%Mn,0.001 wt.%(10 ppm)Fe,630℃ for the holding temperature and holding at 60 mins for the holding time,respectively.Three groups of sludge factors,Chemical Sludge(CSF),Physical Sludge(PSF)and Comprehensive Sludge Factors(and CPSF)were established for prediction of sludge yields and intermetallic sizes in Al-containing Mg alloys.The CPSF with five independent variables including both chemical elements and process parameters gave high accuracy in prediction,as the prediction of the PSF with only the two processing parameters of the melt holding temperature and time showed a relatively large deviation from the experimental data.The Chemical Sludge Factor was primarily designed for small ingot producers and die casters with a limited melting and holding capacity,of which process parameters could be fixed easily.The Physical Sludge Factor could be used for mass production with a single type of Mg alloy,in which the chemistry fluctuation might be negligible.In large Mg casting suppliers with multiple melting and holding furnaces and a number of Mg alloys in production,the Comprehensive Sludge Factor should be implemented to diminish the sludge formation.

Optimization model coupling both chemical compositions and high-temperature characteristics of sintering materials for sintering burden

We developed a mathematical optimization model coupling chemical compositions and high-temperature characteristics of sintering materials, targeting the best quality and lowest cost. The simplex algorithm was adopted to solve this model. Four kinds of imported iron ores, two kinds of Chinese iron ore concentrates, and two kinds of fluxes were selected to verify both the model and the algorithm. The results confirmed the possibility of considering both chemical compositions and high-temperature characteristics of iron ores in the optimization model. This model provides a technical roadmap to obtain a precise mathematical correlation between the lowest cost and the grade of iron in sinters based on the condition of given raw materials, which can provide a reference to adjust the grade of iron in the sintering process for enterprise.

Effects of Chemical Composition and Cooling Process on Structures and Properties of Direct-Quenched Steels

The microstructures and mechanical properties of a series of direct-quenched steels containing,in weight percent,from 0.05 to 0.20 carbon,0.20 to 0.40 silicon,1.10 to 1.70 manganese and at least one microalloying element of vanadium,niobium,titanium and boron have been investigated.After controlled rolling,these steels were cooled in spray water to 400,300 and 200℃,respectively and then cooled in still air.Comparison of the Charpy V-notch impact toughness of direct-quenched steels without subsequent tempering was made with that of direct-quenched steels tempered at 600℃.It is found that an attractive combination of strength and toughness is achived by means of direct-quenching.There exists two types of microstructures in accordance with carbon equivalent.Lath martensitic microstructure is obtained for C>0.4%,granular bainitic microstructures for C.< 0.35%and mixtures of martensite and bainite for C,.in the range of 0.35— 0.40%.The effect of interrupted quenching temperature on microstructure is not significant for low C.steel,but interrupted quenching temperature has a strong effect on microstructure for high C,.steel.

Biodiesel Production from Rhynchophorus ferrugineus Larvae Oil: Physichochemical Properties and Acid Composition of Oil as Affected by Oil Extraction Protocol

Biodiesel, a renewable energy source made from natural oils and fats, can be produced using white raffia larvae as a raw material. These larvae have a high lipid content and a short life cycle, making them suitable for this purpose. One crucial step in biodiesel production is oil extraction, and this study aimed to investigate how the extraction protocol affects the fuel properties of the oil. To study the impact of solvent type, solvent volume, and residence time on oil yield, 200 grams of Rhynchophorus ferrugineus were used in a Soxhlet extractor. The researchers examined the physicochemical properties and fatty acid composition of the crude grease using the European biodiesel standard (EN14214) and gas chromatography methods, respectively. The study found that hexane as a solvent produced the highest oil yield (64.44%) during a four-hour extraction period with a solvent ratio of 300 ml. Furthermore, the hexane-extracted oil had the highest iodine number (3.02 g/100 g) and cetane number (55.69). These values indicate favorable properties for biodiesel production. The Rhynchophorus ferrugineus larvae oil proved to be a rich source of monounsaturated fatty acids (76%), which were found to be significantly affected by the solvent type. Based on quality assessment, Rhynchophorus ferrugineus can be suitable for biodiesel production. In summary, under the given operational conditions, hexane is the most suitable solvent for Rhynchophorus ferrugineus oil extraction for biodiesel production. Further research in optimizing the extraction process can contribute to the efficient utilization of renewable energy sources like white raffia larvae for biodiesel production.

Chemical Composition of Some Saline Lakes in the Tuva Region(Russia)

1 Introduction Salt lakes are very interesting natural objects which can be found in different places in the world.Russia is not an exception.Climate conditions are various in Russia,but the climate is not very hot.In Russia there are a lot of places where salt lakes are spread.One of them is the Tuva region where lakes with different compositions are

A Numerical Study of Densification Behavior of Silicon Carbide Matrix Composites in Isothermal Chemical Vapor Infiltration

We studied the characteristics of two-scale pore structure of preform in the deposition process and the mass transfer of reactant gas in dual-scale pores, and observed the physiochemical phenomenon associated with the reaction. Thereby, we established mathematical models on two scales, respectively, preform and reactor. These models were used for the numerical simulation of the process of ceramic matrix composites densified by isothermal chemical vapor infiltration(ICVI). The models were used to carry out a systematic study on the influence of process conditions and the preform structure on the densification behaviors. The most important findings of our study are that the processing time could be reduced by about 50% without compromising the quality of the material, if the processing temperature is 950-1 000 ℃ for the first 70 hours and then raised to 1 100 ℃.

Preparation of ZrN(ZrON)-SiAION Composite Ceramics via a Pressureless Sintering Process

ZrN-SiAlON composite materials were synthesized at 1 550 ℃ for 6 h via a carbothermal reduction nitridation route using fly ash （≤74 μm）,zircon （≤ 44 μm） and active carbon as starting materials.The processed ZrN-SiAlON composite micropowders were mixed with polyvinyl alcohol as binder to prepare ZrN （ZrON）-SiAlON composite ceramics by carbon-embedded pressureless firing at 1 450,1 500 and 1 550 ℃ for 1 h,respectively.Influences of firing temperature on the phase compositions,microstructure and sintering properties of the ceramics were investigated.The results show that：（1） β-SiAlON based composite ceramics with different compositions can be prepared by controlling firing temperature,and the main crystalline phases of the specimen fired at 1 550 ℃ for 1 h involve ZrN,ZrON and β-SiAlON （z =2,Si4Al2O2N6）; （2） ZrN （ZrON）,β-SiAlON and a Fe-Si based compound can be observed in the microstructures of the specimens fired at different temperatures.ZrN （ZrON） particles distribute homogeneously in the β-SiAlON matrix; （3） raising firing temperature can increase the shrinkage ratio of the ceramics,and the volume shrinkage ratio increases from 19.4％ to 40.3％ when the firing temperature rises from 1 450 to 1 550 ℃.

EXPERT SYSTEM FOR SINTER CHEMICAL COMPOSITION CONTROL BASED ON ADAPTIVE PREDICTION

In order to stabilize the sinter chemical composition,the expert system for composition control based on adaptive prediction has been developed on the basis of modern control theory and artificial intelligence.It has been verified by using real data at No.3 Sintering Plant of Anshan Iron and Steel Co.,and satisfactory results have been obtained.

Effect of Sintering Temperature and Hydrophobic Treatment on the Microstructure and Properties of Copper-Graphite Composites

Copper-graphite composites were prepared by spark plasma sintering(SPS)using coppercoated graphite powder.Hydrophobic surfaces were successfully constructed by chemical etching and surface treatment.The density,metallographic structure,microstructure,Shore hardness,resistivity,water contact angle,and friction/wear properties of the composites were investigated using the Archimedes drainage method,a metallographic microscope,a scanning electron microscope,a hardness tester,a resistometer,a surface science tester,and a friction tester.The results showed that the relative density and Shore hardness of the copper-graphite composites increased slightly from 90.04%and 56 HSD to 92.66%and 59 HSD,respectively,when the sintering temperature increased from 700 to 900℃.The copper and graphite phases in the copper-graphite composites were uniformly distributed with a continuous and network-like structure at various sintering temperatures.The interface between the copper and graphite was in good condition,without any obvious cracks or voids.The optimum process for hydrophobic surface construction included etching with a 1 mol/L K_(2)Cr_(2)O_(7)-H_(2)SO_(4)solution for 1 min,and soaking in a 0.09 mol/L cetylbenzene sulfonic acid alcohol solution for 1 h.The contact angle of the copper-graphite composite reached 130°.Hydrophobic treatment was beneficial for reducing the friction coefficient(from 0.18-0.19 to 0.13-0.15)and the wear rate(from 4.1-6.2×10^(-3)to 1.1-2.1×10^(-3)mm^(3)/(N·m)),demonstrating obvious antifriction and wear-resisting properties.The resistivities of the hydrophobic-treated samples increased slightly,from(4-8)×10^(-7)Ω·m to(5-15)×10^(-7)Ω·m,meeting the resistivity requirements of copper-graphite composite pantograph sliders and current receiver sliders in actual working conditions.

Preparation of β-Sialon/ZrN bonded corundum composites from zircon by nitridation reaction sintering process

β-Sialon/ZrN bonded corundum composites were synthesized using fused white corundum,alumina micro powder,zircon and carbon black by nitridation reaction sintering process. Phase composition and microstructure of the synthesized composites were investigated by X-ray powder diffraction and scanning electronic microscope,and the formation process of the composites was discussed. The results show that the composites with different compositions can be obtained by controlling the heating temperature and contents of zircon and carbon black. The proper temperature to synthesize the composites is 1773 K.

Exploring a balance between strength and ductility of hexagonal BN nanoplatelet reinforced ZK61 magnesium composite

The practical applications of magnesium(Mg)alloys are usually beset by their relatively low strength and limited ductility.Herein we attempt to fabricate hexagonal BN nanoplatelet(BNNP)reinforced ZK61 magnesium composites using a combination of spark plasma sintering and friction stir processing.The resulting composites exhibit microstructural characteristics of homogeneous dispersion of BNNP in Mg matrix with refined equiaxed grains and(0002)basal texture roughly surrounding the pin column surface.Transmission electron microscopy observation illustrates that trace amounts of Mg_(3)N_(2)and MgB_(2)form at BNNP-Mg interface,in which Mg_(3)N_(2)locates at the basal plane of a BNNP and MgB_(2)grows at its open edge.The spatial distribution of Mg_(3)N_(2)and MgB_(2)facilitates interfacial wetting and stronger BNNP-Mg interface in such a way that interfacial products act as anchors bonding between them.In comparison with monolithic ZK61 alloy,the BNNP/ZK61 composites display simultaneous improvements in yield strength,hardness and ductility,achieving good strength-ductility balance.This research is expected to shed some light on BNNP potentials for designing and producing magnesium composites with high strength and good ductility.

Effects of Activated Sintering Process on Properties and Microstructure of W-15Cu Alloy

The effects of activated sintering technology of H2 atmosphere sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying calcining-continuous reduction technology were investigated.The experimental results showed that W-15Cu alloy,consolidated by activated sintering technology of H2 atmosphere sintering for 1 h at 1300 ℃,with 98.5 % relative density,transverse rupture strength 1218 MPa,Vickers hardness HV0.5 378,average grain size about 1.2 μm and thermal conductivity 192 W/m·K,was obtained.In comparison to the normal sintering process,activated sintering process to W-15Cu alloy could be achieved at lower sintering temperature.Furthermore,better properties in activated sintered compacts were obtained,and activated sintering process resulted in finer microstructure and excellent properties.

On the Regression-Tensor Analysis of the Hardening Process of Metal Coatings

This paper constructs and studies a nonlinear multivariate regression-tensor model for substantiation of necessary/sufficient conditions of optimization of technological calculation of multifactor physical and chemical process of hardening of complex composite media for metal coatings. An adaptive a posteriori procedure for parametric formation of the target quality functional of integrative physical and mechanical properties of the designed metal coating has been proposed. The results of the research may serve as elements of a mathematical language when creating automated design of precision nanotechnologies for surface hardening of complex composite metal coatings on the basis of complex tribological and anticorrosive tests.

Preparation of Composites by Nitro Aluminothermic Processes, over β–SiAlON Matrix in the SiAlON-SiC-Al2O3 System

Goal: The goal of the research is preparation of SiAlON-containing composite through nitro aluminothermic processes, by the methods of reactive sintering and hot compaction. Method: The composite CH-6 was obtained by the method of reactive sintering, with further grinding and hot compression in vacuum furnace at 16000°C, under 30 MPa pressure and 10-12 min standing at the final temperature. Precursor was prepared in a thermostat at 150°C temperature by double compression. Pressure equaled to 20-25 MPa. Results: Physical-technical properties of specimens prepared via hot compaction were investigated. Mechanical strength at compression is 1940 MPa;mechanical strength at bending is 490 MPa;elastic module is 199.5 GPa, HV-11.6 GPa. X-Ray diffraction analysis, electron microscopic and X-ray diffraction Microspectral analysis were used to investigate composite microstructure and phase composition. Composite formulation was defined, the main phases of which were: β-SiAlON, corundum and silicium carbide. Conclusion: Composite CH-6 has been selected from the obtained composites, which is characterized by relatively high physical-technical properties: strength, density and hardness. Materials can be used for making high refractory articles, such as jackets to secure thermocouples, furnace bedding, cutting tools for metal and wood treatment, in rocket spatial technology and others.

Chemical composition,pharmacological activity and development strategies of Rubus chingii:A review

Raspberries are used for both food and medicine,but it has not yet attracted widespread attention.In this paper,the chemical constituen of the original plant raspberry.R.chingii is one of the new“Zhe Bawei”medicinal materials selected in 2017.“Zhe Bawei”refers to eight kinds of genuine medicinal materials in Zhejiang Province.The chemical constituents,pharmacological effects,processing,and application of Rubus chingii Hu were reviewed to provide a reference for its further development.Relevant literature in recent years was collected in databases such as China Knowledge Network,Web of Science,Elsevier,PubMed,and X-Mol,using“raspberry”,“Rubus chingii”,“traditional use”,“chemical composition”,“pharmacology”,etc.as keywords individually or in combination.The summary of pharmacological activities shows that the relationship between the pharmacological activities of raspberry is still not deep enough.More in-depth research should be carried out in this direction to explore the mechanism of action of its active ingredients and provide effective reference for the further development of the raspberry industry.In the future,with the participation of more researchers,it is expected to develop innovative drugs based on raspberry for the treatment of diseases.

In-situ fabrication of Al(Zn)-Al_2O_3 graded composite using the aluminothermic reaction during hot pressing

In INs study, the fabrication of multilayer AI（Zn）-A1203 with different volume fractions of A1203 was investigated. A1 and ZnO powders were milled by a plaaetaxy ball mill, after which five-layer functionally graded samples were produced flarough hot pressing at 580~C and 90 MPa pressure for 30 min. Formation of reinforcing A1203 particles occurred in the aluminum matrix via the aluminolkermic reaction. Determination of the ignition temperature of the aluminolkennic reaction was accomplished using differential lkermal and lkermo- gravimelric amlyses. Scaaming electron microscopy, energy dispersive spectroscopy, and X-ray diffractometery amlyses were utilized to characterize the specimens. The lkermal amlysis results showed that the ignition temperatures for the aluminolkennic reaction of layers with the highest and lowest ZnO contents were 667 and 670~C, respectively. Microslxuctural observation and chemical amlysis confirmed the fa- brication of AI（Zn）-A1203 functionally graded materials composites with precipitation of additional Zn in the matrix. Moreover, nearly dense functionally graded samples demonstrated minimum and maximum hacdness values of HV 75 and HV 130, respectively.

预造球强化难制粒精矿烧结工艺

随着进口铁矿石价格的增长,充分利用廉价的难处理铁矿资源成为钢铁企业降本增效的关键。本文针对难制粒精矿在烧结中利用率低的问题,在复合造块法的基础上开发了预造球工艺,显著提高了难制粒精矿的配入量,有效改善了制粒效果与烧结产、质量指标。研究表明,在难制粒精矿配比达到36%时,采用预造球制粒可以使准颗粒平均粒径提高1.53 mm,透气性指数提高0.17。在此基础上,垂直烧结速度提高13.97 mm/min,利用系数提高0.815 t/(m^(2)·h),转鼓强度提高3.39%。预造球烧结中,由于难制粒精矿的分离,常规制粒料部分的制粒性能得到优化,局部碱度得到提高,形成大量的针柱状铁酸钙。在常规制粒料与球团料交界处固相固结与液相固结同时存在,铁酸钙与铁氧化物相互交织,形成球团嵌入式分布的成品矿结构,具有良好的成矿效果和强度性能。

中药远志的炮制研究进展

远志是我国传统中药,具有安神益智、交通心肾、祛痰、消肿等作用,虽然其炮制方法多样,但炮制目的均在于减毒增效。本文对古法炮制中的净制、切制、加辅料炒与不加辅料炒等方法进行了文献概述,并在此基础上,对现代炮制前后化学成分变化及减毒增效机制等方面进行文献分析。现代研究表明,远志的减毒增效机制为远志皂苷的毒性与糖基含量有关,远志皂苷B水解为细叶远志皂苷后胃肠毒性显著降低。现代远志的炮制工艺主要有甘草炙远志、蜜制远志、厚朴汁炙远志、炆远志等,但厚朴汁炙远志、炆远志现代沿用不多,炮制工艺缺乏规范化研究。笔者认为,应加强古法炮制研究,在确定炮制工艺的同时,结合化学成分、药效等方面,开展炮制机制等方面的研究,为远志炮制的合理性提供科学依据,确保临床用药安全。

白术炮制规格及其化学成分与药理作用研究进展

白术是菊科多年生草本植物,药典收载白术和麸炒白术两种饮片规格,主要有效成分为挥发油、内酯、多糖、黄酮和苷类等。主要作用于胃肠道、免疫与神经系统,发挥调节胃肠道、抗肿瘤、抗炎护肝和保护神经等多种药理作用。本文对白术的古今炮制规格及其化学成分和药理作用进行综述,以期为白术的临床应用提供参考。

庐山云雾茶机械化加工技术及品质分析

庐山云雾茶是中国传统十大名茶之一,具有悠久的历史和文化底蕴。研究采摘了不同等级的鲜叶原料,按照摊青、杀青、回潮、揉捻、初烘、做形、干燥的工艺加工成庐山云雾茶,总结了庐山云雾茶加工工艺参数、加工设备和不同等级茶叶的品质特点,并分析了庐山云雾茶化学成分含量,为庐山云雾茶的标准化加工提供科学依据。