Microstructural characterization and mechanical properties of(TiC+TiB)/TA15 composites prepared by an in-situ synthesis method

Titanium matrix composites reinforced with ceramic particles are considered a promising engineering material due to their combination of high specific strength,low density,and high modulus.In this study,the TA15-based composites reinforced with a volume fraction of 10% to 25%(TiB+TiC)were prepared using powder metallurgy and casting technique.Microstructural characterization and phase constitution were examined using optical microscopy(OM),scanning electron microscopy(SEM),and X-ray diffraction(XRD).In addition,the microhardness,room temperature(RT)and high temperature(HT)tensile properties of the composites were evaluated.Results revealed that the reinforcements are distributed uniformly even in the composites with a high volume of TiB and TiC.However,as the volume fraction exceeds 15%,TiB and TiC particles become coarsening and exhibit rod-like and dendritic-like morphology.Microhardness increases gradually from 321.2 HV for the base alloy to a maximum of 473.3 HV as the reinforcement increases to 25vol.%.Tensile test results indicate that a reinforcement volume fraction above 20% is beneficial for enhancing tensile strength and yield strength at high temperatures,but it has an adverse effect on room temperature elongation.Conversely,if the reinforcement volume fraction is below 20%,it can improve high-temperature elongation when the temperature exceeds 600℃.

A Primary Study on Mechanical Properties of Heat-Treated Wood via in-situ Synthesis of Calcium Carbonate

This study aims to improve the value of fast-growing wood and extend the heat-treated wood utilization using inorganic calcium carbonate(CaCO_(3))crystals via an in-situ synthesis method.CaCl_(2)and Na 2CO_(3)solutions with a concentration ratio of 1:1 were successively introduced into the thermally modified poplar wood obtained by steam heat treatment(HT)at 200℃for 1.5 and 3 h,resulting in the in-situ synthesis of CaCO_(3)crystals inside the heat-treated wood.The filling effect was best at the concentration of 1.2 mol/L.CaCO_(3)was uniformly distributed in the cell cavities of the heat-treated wood,and some of the crystals were embedded in the fissures of the wood cell walls.The morphology of CaCO_(3)crystals was mainly spherical and rhombic polyhedral.Three main types of CaCO_(3)crystals were calcite,vaterite,and aragonite.The HT of poplar wood at 200℃resulted in degrading the chemical components of the wood cell wall.This degradation led to reduced wood mechanical properties,including the surface hardness(HD),modulus of rupture(MOR),and modulus of elasticity(MOE).After CaCO_(3)was in-situ synthesized in the heat-treated wood,the HD increased by 18.36%and 16.35%,and MOR increased by 14.64%and 8.89%,respectively.Because of the CaCO_(3)synthesization,the char residue of the 200℃heat-treated wood samples increased by 9.31%and the maximum weight loss rate decreased by 19.80%,indicating that the filling with CaCO_(3)cannot only improve the mechanical properties of the heat-treated wood but also effectively enhance its thermal stability.

Study on the In-situ Synthesis of Aluminum Titanate Sintered by Waste Aluminum Slag

Aluminum titanate was in-situ synthesized by using industrial waste-residue in the aluminum factory and TiO2 as the main raw materials and the influence of different reaction temperatures on the purity and microstructures of synthesized products were mainly discussed. The obtained Al2TiO5 was characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and relevant analytical software. The results show that elevating the sintering temperature can increase the content of aluminum titanate; and at 1420 ℃, it reaches the highest in the synthesized ceramic. When the sintering temperature continues to increase, the produced aluminum titanate will decompose resulting in the drop of its content. Therefore, the optimum sintering temperature of in-situ synthesis of aluminum titanate is determined as 1420 ℃, at which the grains of aluminum titanate grow completely, the purity of aluminum titanate is 89.3wt%., the highest density is 2.75 g/cm^3, and the porosity is 9%.

In-situ Synthesis of ZSM-5 with Different Si/AlRatios on Honeycomb-shaped Cordierite and their Behavior on NO Decomposition

Zeolites ZSM-5 with different Si/Al ratios were in-situ synthesized on the surface ofhoneycomb-shaped cordierite support for the first time. Characterizations of XRD and SEM wereperformed and it has been proved that the zeolite ZSM-5 was grown on the surface of the cordieritehomogeneously. NO decomposition on the Cu exchanged ZSM-5/cordierite monolith catalysts wasalso studied. It was found that the monolith catalysts have a fine initial activity at 673K and GHSVof 10,000h-1. Such method should be a good way to make auto exhaust converter with monolithcatalyst for NOx removal.

Study of the Performance and Microstructure of CeB_6/B_4C Ceramic Composite via in-situ Synthesis

CeB6/B4C ceramic composite was fabricated by hot-pressed sintering via in-situ synthesis reaction among B4C, CeOand C. The effects of CeB6 content on the performance and microstructure of CeB6/B4C composites were investigated. As the content of CeB6 was 2.42%, the microhardness of CeB6/B4C composite reached the maximum of 40.64 GPa, which was higher than that of monolithic B4C by 52.5%. As the content of CeB6 was 4.89%, the flexibility strength and the fracture toughness of CeB6/B4C composite reached the peak values of 346.7 MPa and 5.95 MPa·m1/2 respectively, which were higher than those of monolithic B4C by 17.96% and 61.7% respectively. The integrated mechanical property of CeB6/B4C ceramic composite with the 4.89% CeB6 content is optimal. It was also found that as in-situ synthesis of CeB6, the crystal grain growth was inhibited, and crystallite arrangement was so compact that the pores gradually reduced. The main fracture mode of CeB6/B4C ceramic composite was intercrystalline rupture, while the transcrystalline rupture was minor.

In-situ Synthesis of ZSM-5 Zeolite from Metakaolin/Spinel and Its Catalytic Performance on Methanol Conversion

ZSM-5 zeolite was in-situ synthesized from metakaolin or s alumina sources, respectively. The ZSM-5 zeolite was characterized pinel by incorporating additional silica and by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared （FT-IR） spectroscopy and N2 adsorption measurement. This supported zeolite was tested on the methanol to propylene （MTP） processes. Experimental results showed that the ZSM-5 zeolite exhibited high selectivity for propylene. The yield of propylene on ZSM-5 zeolite made from metakaolin was increased by 17.73%, while that on ZSM-5 zeolite made from spinel was raised by 9.90%, compared to that achieved with the commercial ZSM-5 zeolite. The significant increase in propylene production is probably due to the distinctive morphology of the ZSM-5 zeolite, which possessed a rough external surface covered with sphere-like particles and distribution of small crystals sized at around 400--500 nm. This morphology could help to generate more crystal defects so that more active centers could be exposed to the reaction mixture. In addition, the zeolite product had a gradient pore distribution and many medium Brǒnsted acid sites, both of which might also contribute to the increased propylene production.

In-Situ Synthesis and Characteristics of TiC-Fe Cermet Graded Composite Coating on a Steel Substrate

By means of an inherent elevated-temperature of poured liquid steel,a Ti-C-30wt%Fe preform,which was pre-placed in a mould cavity,was directly ignited and a combustion synthesis reaction took place.As a result,a TiC-Fe cermet coating with a thickness of about 10mm was simultaneously synthesized on the solidified steel matrix.The synthesized coating exhibits a feature of graded composite structure,in which both the amount and size of TiC particles decrease gradually with an increasing distance from the furface of the coating.Moreover,by a proper casting technique,the pores formed during the combustion synthesis of the preform could be centrally distributed in 2-3mm in outer layer of the coating.When this outer porous layer was worn off,the rest coating with a thickness of about 8mm possesses a dense structure and a high abrasive wear resistance.

Center Distance and Pouring Temperature on in-situ Synthesis of WC_P/Fe Composite Coating

Tungsten carbide （WC） particles can be in-situ synthesized through the reaction between tungsten wires and molten of gray cast iron. The different composite coatings were obtained by adjusting the pouring temperature and the center distance of tungsten wires, and were comparatively observed by X-ray diffraction, scanning electron microscopy, and two-body abrasive wear tests. The results show that the intensities of the WC peaks increase by the increasing pouring temperature, and firstly become strong and then weak by the increasing center distance. In case of the pouring temperature 1 400 ℃ and the center distance 0.5mm, the formed WC particles present quadrilateral and triangle-structure and are homogenously distributed in the matrix. The wear rate of the composite coatings for stable center distance gradually increases by increasing the loads, however, at a constant pouring temperature, it firstly decreases from 5.91 to 2.97 mg/cm2·h, and slightly increases to 3.98 mg/cm2·h by increasing the center distance.

In-situ synthesis of Al_3Ti particles reinforced Al-based composite coating

Using titanium wires （99.5%, 200 μm in diameter） as a reactive source, an Al-based composite coating reinforced by titanium tri-aluminide （A13Ti） particles was fabricated by infiltration plus in-situ methods. According to the differential thermal analysis （DTA） curve, the reactive temperature between Ti wires and A1 matrix can be determined at 890 ℃. The obtained composite coatings were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and microhardness and wear test. The experimental results show that when holding period is 20 min at 890℃, the titanium wires react completely to in-situ synthesize Al3Ti particles, which presents blocky and strip-like states. The microhardness of in-situ synthesized Al3Ti particles is about 4.5 times that of the Al-matrix. Under the condition of dry sliding at 10 N load, compared with the unreinforced Al matrix, the composite coating fabricated with 20 min offers unique wear resistance behavior, and its wear mechanism is that the adhesive wear and abrasive wear coexist.

Formation of ZrB2in MgO-C Composite Materials Using In-Situ Synthesis Method

ZrB2 in MgO-C composite materials obtained by both microwave sintering synthesis and in-situ reaction at lower temperature was investigated. The test result shows that 66.67 % of reactant changed into Zrb2, and the other form Al2O3, which could optimize the properties of carbon containing materials. Therefore, the method of in situ synthesizing ZrB2 acting as antioxidant in carbon containing materials is considered as one of best ways to reduce the cost and ZrB2 as refractories is used on a large-scale.

In-Situ Synthesis of Terbium Complex with Salicylic Acid in Silica Matrix by a Two-Step Sol-Gel Process

A process for in situ synthesis of terbium complex with salicylic acid by a two-step solgel method in silica matrix has been proposed. The luminescence properties of the silica gelscodoped with terbium and salicylic acid have also been discussed with respect to that of the geldoped with terbium and that of pure terbium complex with salicylic acid.

In-situ Synthesis of Binderless ZSM-5 Zeolitic Coatings on Aluminum

ZSM-5 zeolitic coatings on aluminum have been prepared successfully by in-situhydrothermal synthesis method and ZSM-5/Al monolith was formed. The effects of pH value andcrystallization time on the in-situ synthesis were discussed.

In-Situ Synthesis of AlN Powders and Composite AlN Powders with Yttrium Addition

Using Al Mg and Al Mg Y alloys as raw materials and nitrogen as gas reactants, AlN powders and composite AlN powders by in situ synthesis method were prepared. AlN lumps prepared by the nitriding of Al Mg and Al Mg Y alloys have porous microstructure, which is favorable for pulverization. They have high purity, containing 1.23%(mass fraction) oxygen impurity, and consisted of AlN single phase. The average particle size of AlN powders is 6.78 μm. Composite AlN powders consist of AlN phases and rare earth oxide Y 2O 3 phase. The distribution of particle size of AlN powders shows two peaks. In view of packing factor, AlN powders with such size distribution can easily be sintered to high density.

Science Letters; In-situ synthesis and luminescence properties of titanium oxide gels containing 1,10-phenanthroline europium(Ⅲ) complex

It is difficult to directly dope europium complexes in gel because the excessive water or high acidic condition may lead to their decomposition. We prepared a novel homogeneous TiO2 gel containing Eu-phen complexes by using an in-situ synthesis method. The formation of Eu-phen complexes in sol-gel derived TiO2 was confirmed by luminescence excitation spectra. The effects of temperature and aging time on in-situ synthesis are discussed. The luminescence spectra of gel containing europium complexes were also compared with the pure Eu-phen complexes.

In-situ Synthesis of Cr_(3)C_(2) Nanosheets by Carbon Reduction Route from Cr_(2)AlC

Carbon black and Cr_(2)AlC were used as raw materials to obtain a large number of Cr_(3)C_(2)nanosheets by means of the molten salt heat treatment at 1100℃for 1.5 hours.Results showed that carbon black can promote the decomposition of a large number of Cr_(2)AlC to form Cr_(3)C_(2)and Cr_(7)C_(3)nanoparticles at 1100℃in the absence of molten salt.Under a molten salt environment,carbon black can promote the complete decomposition of Cr_(2)AlC to form Cr_(3)C_(2)and Cr_(7)C_(3)nanosheets.The thickness of chromium carbide nanosheets is approximately 10-20 nm,and the length is approximately 100-200 nm.The addition of excess carbon black can promote the complete decomposition of Cr_(2)AlC into a material with Cr_(3)C_(2)as the main phase.

Templated synthesis of transition metal phosphide electrocatalysts for oxygen and hydrogen evolution reactions

Transition metal phosphides(TMPs)have been regarded as alternative hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts owing to their comparable activity to those of noble metal-based catalysts.TMPs have been produced in various morphologies,including hollow and porous nanostructures,which are features deemed desirable for electrocatalytic materials.Templated synthesis routes are often responsible for such morphologies.This paper reviews the latest advances and existing challenges in the synthesis of TMP-based OER and HER catalysts through templated methods.A comprehensive review of the structure-property-performance of TMP-based HER and OER catalysts prepared using different templates is presented.The discussion proceeds according to application,first by HER and further divided among the types of templates used-from hard templates,sacrificial templates,and soft templates to the emerging dynamic hydrogen bubble template.OER catalysts are then reviewed and grouped according to their morphology.Finally,prospective research directions for the synthesis of hollow and porous TMP-based catalysts,such as improvements on both activity and stability of TMPs,design of environmentally benign templates and processes,and analysis of the reaction mechanism through advanced material characterization techniques and theoretical calculations,are suggested.

The structure-directing role of heterologous seeds in the synthesis of zeolite

Zeolites have been widely used as catalysts,ion-exchangers,and adsorbents in chemical industries,detergent industry,steel industry,glass industry,ceramic industry,medical and healthfield,and environmentalfield,and recently applied in energy storage.Seed-assisted synthesis is a very effective approach in promoting the crystallization of zeolites.In some cases,the target zeolite cannot be formed in the absence of seed zeolite.In homologous seed-assisted synthesis,the structure of the seed zeolite is the same to that of the target zeolite,while the structure of the seed zeolite is different to that of the target zeolite in the heterologous seed-assisted synthesis.In this review,we briefly summarized the heterologous seed-assisted syntheses of zeolites and analyzed the structure-directing effect of heterologous seeds and surveyed the“common composite building units(CBUs)hypothesis”and the“common secondary building units(SBUs)hypothesis”.However,both hypotheses cannot explain all observations on the heterologous seed-assisted syntheses.Finally,we proposed that the formation of the target zeolite does need nuclei with the structure of target zeolite and the formation of the nuclei of the target zeolite can be promoted by either the undissolved seed crystals with the same CBUs or SBUs to the target zeolite or by the facilitated appropriate distribution of the specific building units due to the presence of the heterologous seed that does not have any common CBUs and SBUs with the target zeolite.

Facile synthesis of hierarchical NaX zeolite from natural kaolinite for efficient Knoevenagel condensation

Zeolite catalysts have found extensive applications in the synthesis of various fine chemicals.However,the micropores of zeolites impose diffusion limitations on bulky molecules,greatly reducing the catalytic efficiency.Herein,we explore an economic and environmentally friendly method for synthesizing hierarchical NaX zeolite that exhibits improved catalytic performance in the Knoevenagel condensation reaction for producing the useful fine chemical 2-cyano-3-phenylacrylate.The synthesis was achieved via a low-temperature activation of kaolinite and subsequent in-situ transformation strategy without any template or seed.Systematic characterizations reveal that the synthesized NaX zeolite has both intercrystalline and intra-crystalline mesopores,smaller crystal size,and larger external specific surface area compared to commercial NaX zeolite.Detailed mechanism investigations show that the inter-crystalline mesopores are generated by stacking smaller crystals formed from in-situ crystallization of the depolymerized kaolinite,and the intra-crystalline mesopores are inherited from the pores in the depolymerized kaolinite.This synthesis strategy provides an energy-saving and effective way to construct hierarchical zeolites,which may gain wide applications in fine chemical manufacturing.

Optimal synthesis of heat-integrated distillation configurations using the two-column superstructure

In the realm of the synthesis of heat-integrated distillation configurations,the conventional approach for exploring more heat integration possibilities typically entails the splitting of a single column into a twocolumn configuration.However,this approach frequently necessitates tedious enumeration procedures,resulting in a considerable computational burden.To surmount this formidable challenge,the present study introduces an innovative remedy:The proposition of a superstructure that encompasses both single-column and multiple two-column configurations.Additionally,a simultaneous optimization algorithm is applied to optimize both the process parameters and heat integration structures of the twocolumn configurations.The effectiveness of this approach is demonstrated through a case study focusing on industrial organosilicon separation.The results underscore that the superstructure methodology not only substantially mitigates computational time compared to exhaustive enumeration but also furnishes solutions that exhibit comparable performance.