Investigation of Microstructure, Microhardness and Thermal Properties of Ag-In Intermetallic Alloys Prepared by Vacuum Arc Meltings

Ag-In intermetallic alloys were produced by using vacuum arc furnace. Differential Scanning Calorimetry(DSC) and Energy Dispersive X-Ray Spectrometry(EDX) were used to determine the thermal properties and chemical composition of the phases respectively. Microhardness values of Ag-In intermetallics were calculated with Vickers hardness measurement method. According to the experimental results, Ag-34 wt%In intermetallic system generated the best results of energy saving and storage compared to other intermetallic systems. Also from the microhardness results, it was observed that intermetallic alloys were harder than pure silver and Ag-26 wt%In system had the highest microhardness value with 143.45 kg/mm^(2).

A review on the multi-scaled structures and mechanical/thermal properties of tool steels fabricated by laser powder bed fusion additive manufacturing

The laser powder bed fusion(LPBF) process can integrally form geometrically complex and high-performance metallic parts that have attracted much interest,especially in the molds industry.The appearance of the LPBF makes it possible to design and produce complex conformal cooling channel systems in molds.Thus,LPBF-processed tool steels have attracted more and more attention.The complex thermal history in the LPBF process makes the microstructural characteristics and properties different from those of conventional manufactured tool steels.This paper provides an overview of LPBF-processed tool steels by describing the physical phenomena,the microstructural characteristics,and the mechanical/thermal properties,including tensile properties,wear resistance,and thermal properties.The microstructural characteristics are presented through a multiscale perspective,ranging from densification,meso-structure,microstructure,substructure in grains,to nanoprecipitates.Finally,a summary of tool steels and their challenges and outlooks are introduced.

Effects of BN on the Mechanical and Thermal Properties of PP/BN Composites

In order to explore the thermal conductivity of polypropylene(PP)/hexagonal boron nitride(BN) composites,PP composites filled with different proportions of BN were prepared through extrution compounding,injection moulding and compression moulding.The composites were filled with BN particles of 5 and 20 μm respectively,and their mass fractions in composites were considered.Percentage of BN was varied from 0 to 25wt% in steps of 5wt%.The effects of BN filler on mechanical properties of the composites were evaluated.The thermal behaviors were studied using DSC and TGA,and the thermal conductivity was also investigated by Laser Flash Device and the Model of 3D Heat Conduction respectively.The experimental results show that impact strength of PP/BN can be enhanced with the addition of BN,but that composites exhibit lower breaking elongation & tensile strength when compared to unfilled ones.It is found that mass fraction of BN influenced the final thermal stability and degree of crystallization of PP matrix,the degree of crystallization of PP with 15wt% of 20 μm BN can be improved by 25% than neat PP.Meanwhile,crystallization temperatures of PP composites are elevated by about 10 ℃.The thermal conductivity results demonstrate that the maximum value of the thermal conductivity is achieved from PP/BN with 20wt% of 20 μm BN,higher than that of pure PP by 95.65%,close to the simulation one.

Thermo-Physical Potential of Recycled Banana Fibers for Improving the Thermal and Mechanical Properties of Biosourced Gypsum-Based Materials

The development of bio-sourced materials is essential to ensuring sustainable construction;it is considered a locomotive of the green economy.Furthermore,it is an abundant material in our country,to which very little attention is being given.This work aims to valorize the waste of the trunks of banana trees to be used in construction.Firstly,the physicochemical properties of the fiber,such as the percentage of crystallization and its morphology,have been determined by X-ray diffraction tests and scanning electron microscopy to confirm the potential and the impact of the mode of drying on the quality of the banana fibers,with the purpose to promote the use of this material in construction.Secondly,the results obtained with the gypsum matrix allowed us to note a preponderant improvement in the composite’s thermal properties thanks to the variation of the banana fiber additive.Thirdly,the impact of the nature of the banana fiber distribution(either fiber mixed in matrix or fiber series model)on the flexural and compressive strengths of the composites was studied.The results obtained indicate that the insulation gain reaches up to 40%.It depends on the volume fraction and type of distribution of the banana fibers.However,the thermal inertia of the composites developed,represented by thermal diffusivity and thermal effusivity,was studied.Results indicate a gain of 40%and 25%,respectively,in terms of thermal diffusivity and thermal effusivity of the developed composites compared to plaster alone.Concerning the mechanical properties,the flexural strength depends on the percentage of the volume fraction of banana fibers used,and it can reach 20%more than the flexural strength of plaster;nevertheless,there is a significant loss in terms of the compressive strength of the studied composites.The results obtained are confirmed by the microstructure of the fiber banana.In fact,the morphology of the banana fibers was improved by the drying process.It reduces the amorphous area and improves the cellulosic crystalline surfaces,which assures good adhesion between the fiber and the matrix plaster.Finally,the dimensionless coefficient analysis was done to judge the optimal proportion of the banana fiber additive and to recommend its use even on false ceilings or walls.

Composite Panels from the Combination of Rice Husk and Wood Chips with a Natural Resin Based on Tannins Reinforced with Sugar Cane Molasses Intended for Building Insulation: Physico-Mechanical and Thermal Properties

The objective of this work is to develop new biosourced insulating composites from rice husks and wood chips that can be used in the building sector. It appears from the properties of the precursors that rice chips and husks are materials which can have good thermal conductivity and therefore the combination of these precursors could make it possible to obtain panels with good insulating properties. With regard to environmental and climatic constraints, the composite panels formulated at various rates were tested and the physico-mechanical and thermal properties showed that it was essential to add a crosslinker in order to increase certain solicitation. an incorporation rate of 12% to 30% made it possible to obtain panels with low thermal conductivity, a low surface water absorption capacity and which gives the composite good thermal insulation and will find many applications in the construction and real estate sector. Finally, new solutions to improve the fire reaction of the insulation panels are tested which allows to identify suitable solutions for the developed composites. In view of the flame tests, the panels obtained are good and can effectively combat fire safety in public buildings.

An Explosive Organic/Inorganic Hybrid: Synthesis and Thermal Property of Octa(2,4-dinitrophenyl)silsesquioxane

Octaphenylsilsesquioxane(OPhS) was prepared by a modifying method and a new core-shell nanocomposite, octa(2,4-dinitrophenyl)silsesquioxane, [(R_2PhSiO_ 1.5)_8, R=—NO_2, ODNPhS], was synthesized by nitration of OPhS in a mixed acid solution of nitric and sulfuric acids at about 60 ℃. Their molecular structures were determined by DRIFTS, 1H NMR, 13C NMR spectra analysis. The thermal analysis shows that ODNPhS is an explosive that detonates at about 420 ℃.

Synthesis,Structure and Thermal Property of a Cobalt Supramolecular Complex Containing N-[(4-Carboxyphenyl)-sulfonyl]glycine

Utilizing N-[（4-carboxyphenyl）-sulfonyl]glycine （abbreviated as cbsglyH3）,a new cobalt complex [Co（cbsglyH）（bipy）2]3H2O （bipy = 2,2＇-bipyridine） has been synthesized under mild conditions and characterized by IR,elemental analysis,thermogravimetric analysis and X-ray diffraction analysis. It crystallizes in the monoclinic system,space group C2/c with a = 34.978（3）,b = 12.0437（11）,c = 20.0041（19） ,β = 122.2990（10）°,V = 7123.0（11） 3,Z = 8,C29H28CoN5O9S,Mr = 681.55,μ = 0.593 mm-1,Dc = 1.271 Kg/m3,F（000） = 2816,the final R = 0.0434 and wR = 0.1351. The title complex is a monomeric compound which is further assembled by intermolecular hydrogen bonds into a 3-D supramolecular network. Thermogravimetric analysis illustrates that this complex begins decomposing at 100 ℃ and decompounding completely at 560 ℃.

Experimental study on thermal and mechanical properties of tailings-based cemented paste backfill with CaCl_(2)·6H_(2)O/expanded vermiculite shape stabilized phase change materials

CaCl_(2)·6H_(2)O/expanded vermiculite shape stabilized phase change materials(CEV)was prepared by atmospheric impregnation method.Using gold mine tailings as aggregate of cemented paste backfill(CPB)material,the CPB with CEV added was prepared,and the specific heat capacity,thermal conductivity,and uniaxial compressive strength(UCS)of CPB with different cement-tailing ratios and CEV addition ratios were tested,the influence of the above variables on the thermal and mechanical properties of CPB was analyzed.The results show that the maximum encapsulation capacity of expanded vermiculite for CaCl_(2)·6H_(2)O is about 60%,and the melting and solidification enthalpies of CEV can reach 98.87 J/g and 97.56 J/g,respectively.For the CPB without CEV,the specific heat capacity,thermal conductivity,and UCS decrease with the decrease of cement-tailing ratio.For the CPB with CEV added,with the increase of CEV addition ratio,the specific heat capacity increases significantly,and the sensible heat storage capacity and latent heat storage capacity can be increased by at least 10.74%and 218.97%respectively after adding 12%CEV.However,the addition of CEV leads to the increase of pores,and the thermal conductivity and UCS both decrease with the increase of CEV addition.When cement-tailing ratio is 1:8 and 6%,9%,and 12%of CEV are added,the 28-days UCS of CPB is less than 1 MPa.Considering the heat storage capacity and cost price of backfill,the recommended proportion scheme of CPB material presents cement-tailing ratio of 1:6 and 12%CEV,and the most recommended heat storage/release temperature cycle range of CPB with added CEV is from 20 to 40℃.This work can provide theoretical basis for the utilization of heat storage backfill in green mines.

Influence of Al^(3+) doping on the energy levels and thermal property of the 3.5MgO·0.5MgF_2·GeO_2:Mn^(4+) red-emitting phosphor

A series of Al3+-doped 3.5MgO·0.5MgF2·GeO2:Mn4+red-emitting phosphors is synthesized by high temperature solid-state reaction. The broad excitation band at 300 nm–380 nm, resulting from the4A2→4T1transition of Mn4+,exhibits a blue shift with the increase of Al2O3 content. The observation of the decreased Mn4+–O2-distance is explained by the crystal field theory. The temperature-dependent photoluminescence spectra with various amounts of Al2O3 content are comparatively measured and the calculation shows that the activation energy increases up to 0.41 eV at the Al2O3 content of 0.1 mol. The maximum phonon densities of state for these samples are calculated from Raman spectra and they are correlated with the thermal properties.

Phase Transition and Negative Thermal Expansion Property of ZrMnMo_3O_(12)

A novel material of ZrMnMo3012 with negative thermal expansion is presented. The phase transition temperature and coemcient of thermal expansion （CTE） are investigated by temperature-dependent x-ray diffraction and Raman spectra. It is shown that ZrMnMo3012 adopts monoclinic structure with space group P21/a （No. 14） from 298 to 358K and transforms to orthorhombic with space group Pnma （No. 62） above 363K. The linear CTE obtained from the results of XRD refinement is -2.80 × 10-6 K-1 from 363 to 873 K. The CTE of the bulk cylinder ceramic measured by a thermal dilatometer is -4.7× 10-6 K-1 from 373 to 773K approximatively.

Synthesis,Crystal Structure and Thermal Property of a 2D Brick Wall Framework Constructed from a New Mononuclear Complex

One new coordination polymer with the chemical formula [CoCu2L2·K2·1.5C2H5OH]n（H4L = 2-hydroxy-3-[（E）-（{3-[（2-hydroxybenzoyl）amino]propyl}imino）methyl] benzoic acid） has been synthesized based on the slow diffusion method,and characterized by IR spectroscopy,thermalgravimetric and X-ray diffraction analysis.It crystallizes in the monoclinic system,space group P21/n with a = 11.98860（10）,b = 24.4279（3）,c = 14.9008（2） ,β = 104.7490（10）°,V = 4220.01（8） 3,Z = 2,Mr = 1009.94,Dc = 1.590 g/cm3,F（000） = 2056,μ（MoKα） = 1.649 mm-1,the final R = 0.0411 and wR = 0.1178 for 5920 observed reflections with I 2σ（I）.The compound possesses a 2D brick wall structure constructed from trinuclear units.

Hydrothermal Synthesis, Crystal Structure and Photoluminescent Property of a Novel Complex [Zn(OHCT)(1,2-BDC)]_n

A novel ligand 11-oxa-4,5,9,10,12,13-hexaaza-cyclopenta [b] triphenylene （OHCT） and its coordination polymer [Zn（OHCT）（1,2-BDC）]n 1 （1,2-BDC = 1,2-benzenedicarboxylate） were synthesized and characterized. Crystallographic data for OHCT： C14H6N6O5, Mr = 274.25, monoclinic, space group P21/c, a = 10.755（3）, b = 11.710（4）, c = 9.516（3） , β = 108.457（4）o, V = 1136.9（6） 3, Dc = 1.602 g/cm3, μ（MoKα） = 0.111 mm-1, F（000） = 560, Z = 4, the final R = 0.1534 and wR = 0.39709. Crystallographic data for 1： C22H10ZnN6O5, Mr = 503.73, triclinic, space group P , a = 6.1411（5）, b = 10.9111（9）, c = 14.1925（1） , α = 89.1830（1）, β = 79.3030（1）, γ = 84.6350（1）o, V = 930.36（1） 3, Dc = 1.798 g/cm3, μ（MoKα） = 1.376 mm-1, F（000） = 508, Z = 2, the final R = 0.0323 and wR = 0.0789. 1 has been obtained by using hydrothermal synthesis and characterized by elemental analysis, IR spectrum, thermal analysis, fluorescence spectrum and single-crystal X-ray diffraction. In complex 1, the zinc atom is five-coordinated with three carboxylate oxygen atoms from three different 1,2-BDC ligands and two nitrogen atoms from one OHCT ligand, showing a distorted trigonal bipyramidal configuration.

Improved thermal property of strained InGaAlAs/AlGaAs quantum wells for 808-nm vertical cavity surface emitting lasers

The 808-nm vertical cavity surface emitting laser(VCSEL) with strained In_(0.13)Ga_(0.75)Al_(0.12)As/Al_(0.3)Ga_(0.7)As quantum wells is designed and fabricated. Compared with the VCSELs with Al_(0.05)Ga_(0.95)As/Al_(0.3)Ga_(0.7)As quantum wells, the VCSEL with strained In_(0.13)Ga_(0.75)Al_(0.12)As/Al_(0.3)Ga_(0.7)As quantum wells is demonstrated to possess higher power conversion efficiency(PCE) and better temperature stability. The maximum PCE of 43.8% for 10-μm VCSEL is achieved at an ambient temperature of 30°C. The size-dependent thermal characteristics are also analyzed by characterizing the spectral power and output power. It demonstrates that small oxide-aperture VCSELs are advantageous for temperature-stable performance.

Synthesis,Characterization and Thermal Property of the Aluminum Boroxine-linked Compound with N-aryl Substituted β-Diketiminato Ligand

The boroxine-linked organic aluminum compound LAl[OB（3-C4H3O）]2（μ-O） was accomplished by reacting LAl H2 {L =（Z）-4-[（2,6-diisopropylphenyl）amino]pent-3-en-2-ylidene-2,6-diisopropylaniline} with furan-3-ylboronic acid in good yield.The title compound belongs to the orthorhombic system,space group Pnma with a = 10.9774（15）,b = 19.369（3）,c = 17.362（3） A,V = 3691.5（9） A^3,C37H47 Al B2N2O5,Mr = 648.37,Z = 4,Dc = 1.167 Mg/m^3,μ（Mo Kα） = 0.097 mm^–1,F（000） = 1384,S = 1.000,the final R = 0.0589 and w R = 0.1445 for 9138 observed reflections（I 〉 2σ（I）） and R = 0.0683 and w R = 0.1517 for all data.This compound is an unique example of a spiro-centered aluminum atom,showing the inorganic Al O3B2 ring fused to the organic C3N2 part.It was characterized by 1H NMR,IR,elemental analysis,and single-crystal X-ray structural analysis.Furthermore,the compound was studied by TG analysis as well as DSC.

Synthesis, Crystal Structure and Thermal Property of a Manganese(II) 4-Carboxyphenoxyacetate Complex

The manganese(II) complex, [Mn(phen)2(4-CPOA)(H2O)]?5H2O (4-CPOAH2 = 4- carboxyphenoxyacetic acid) has been synthesized and characterized by elemental analyses, IR, TG and single-crystal X-ray diffraction. The crystal is of monoclinic, space group C2/c, with a = 27.471(3), b = 18.490(4), c = 14.507(3) ?, β = 115.13(3)o, V = 6671(3) ?3, Z = 8, Mr = 717.58, Dc= 1.429 g/cm3, μ = 0.462 mm–1, F(000) = 2984, the final R = 0.0535 and wR = 0.1200 for 5413 observed reflections with I > 2σ(I). The Mn(II) atom is coordinated by one O atom of 4-carboxy- phenoxyacetate, four N atoms of two 1,10-phenanthroline and one water molecule, residing in a distorted octahedral environment. A supramolecular network structure is formed by hydrogen bonds and π-π stacking interactions.

Effect of Rare Earth Elements on Thermal Fatigue Property of Low Chromium Semi-Steel

The effect of rare earth elements on eutectic carbide′s morphology of low chromium semi steel in as cast state and after heat treatment was investigated, and accordingly, the thermal fatigue property of this material was studied. The results show that RE can improve the eutectic carbide′s morphology, inhibit the formation and propagation of thermal fatigue cracks, therefore, promote the thermal fatigue property, which is more noticeable in case of the RE modification in combination with heat treatment. The optimal thermal fatigue property can be obtained when treated with 0.2% RE modification as well as normalization at 950 ℃ for 3 h.

Thermal Fatigue Property of Cr-W-Mo-Ni-Mn-RE Ferric-Base Hardfacing Layer

The thermal fatigue property of Cr-W-Mo-Ni-Mn-RE ferric-base hardfacing layer was investigated. The results show that the generation and propagation of thermal fatigue cracks prefer the parts of oxidation and etching of the grain boundary, the joint efforts of cycle stress and oxidation at high temperatures are the main factors in the generation and propagation of thermal fatigue cracks. When the temperatures is below 600 ℃, the Cr-W-Mo-Ni-Mn-RE ferric-base hardfacing layer has higher ability of thermal fatigue resistance. The function of the alloy and rare earth elements was discussed.

Effect of silane and zirconia on the thermal property of cathodic electrophoretic coating on AZ31 magnesium alloy

Magnesium alloys,the lightest structural metal,are used in the field of aeronautics and astronautics more and more,however they are still limited for the poor corrosion resistant and high temperature property.In order to satisfy the need of long time store and short time operation at elevated temperature,coating with excellent corrosion resistance and thermal resistance was prepared on the surface of Mg alloy AZ31B.The cathodic electrophoretic deposition was applied for the preparation of coating.The bonding of organic electrophoretic deposition coating with substrate was improved using silane pretreatment.Nano-ZrO_(2) powder treated by silane was added into electrophoretic deposition solution.The corrosion resistance property of electrophoretic coating was evaluated using Machu test,and thermal characteristic using the thermal shock experiment and DTA respectively.The morphology of the coating was examined by SEM.It is found that both the corrosion resistant and thermal shock resistant properties can be improved by modifying the Mg specimen with APS silane,while adding nano-ZrO_(2)powder treated by GPS silane to the coating has the optimal effect.And the results also show that the main reason of the coating damage after thermal shock at 400°C or 500°C is mainly for the thermal stress.

Effect of microstructure on the mechanical, thermal, and electronic property measurement of ceramic coatings

Ceramic materials were investigated as thermal barrier coatings and electrolytes. Electrophoretic deposition（EPD） and physical vapor deposition（PVD） were employed to fabricate samples, and the mechanical properties and microstructure were examined by nanoindentation and microscopy, respectively. Yttria-stabilized zirconia/alumina（YSZ/Al2O3） composite coatings, a candidate for thermal barrier coatings, yield a kinky, rather than smooth, load–displacement curve. Scanning electron microscope（SEM） examination reveals that the kinky curve is because of the porous microstructure and cracks are caused by the compression of the indenter. Li0.34La0.51 Ti O2.94（LLTO） on Si/Sr Ru O3（Si/SRO） substrates, an ionic conductor in nature, demonstrates electronic performance. Although SEM images show a continuous and smooth microstructure, a close examination of the microstructure by transmission electron microscopy（TEM） reveals that the observed spikes indicate electronic performance. Therefore, we can conclude that ceramic coatings could serve multiple purposes but their properties are microstructure-dependent.

A THEORETICAL APPROACH TO THERMAL PROPERTY OF ARRAY OF CYLINDERS EMBEDDED IN HOMOGENEOUS MATRIX

We investigate in this article the thermal coliductivity of array Of cylinders embedded in a homogeneous matrix. Using Green's function, we confirm that the method invented by Rayleigh can be generalized to deal with thermal property of these systems. A technique for calculating effective thermal conductivities of these systems is proposed. As an example, we consider a system with square symmetry, and a neat formula for effective thermal conductivity is derived. We show that the method also includes the proof of Keller theorem.