Sintering Process Parameters Research Articles

Response surface methodology and process optimization of spark plasma sintered parameters of Ti20Al20Cr5Nb5Ni19Cu12Co19 high entropy alloy

Study was carried out on the effect of milling and sintering process parameters on the relative density and microhardness property of a septenary non-equiatomic Ti20Al20Cr5Nb5Ni19Cu12Co19 high entropy alloy fabricated via spark plasma sintering (SPS) process at 100 °C/min constant heating rate, 5 min dwell time, and at a pressure of 50 MPa. A predictive model was developed through response surface methodology (RSM) using the SPS sintering temperature (ST) and milling time (MT) as the process variables. In order to reduce the number of experimental runs, the design of experiment (DOE) technique was used, to eventually avoid the trial-and-error process associated with conventional experimental procedures. The user-defined design (UDD) of the RSM was used to forecast the optimal operating parameters, and the outcome was validated by experiments. Findings indicate that MT and ST are important in achieving high densification, which leads to high densification and mechanical properties. Optimization model shows that, at MT of 7.20115 h and ST of 899.742 °C, desirable responses of 99.9 % relative density, percentage porosity of 0.0999994 % and a micro-hardness value of 835.21 HV can be attained.

DETERMINATION OF OPTIMAL PARAMETERS OF SINTERING OF ROLLING SCALE

This article presents the results of studies conducted to determine the optimal parameters of sintering of rolled scale in a mixture with iron-containing steelmaking waste. The conducted studies of sintering of rolled scale have shown that the gas permeability of the charge depends on a number of physical properties, the size and shape of the grains, the amount of return, the height of the charge layer, and the moisture content of the charge. The initial gas permeability strongly depends on the degree of humidification of the agglomeration charge, especially when sintering small classes of materials under study. The maximum gas permeability of the charge is ensured with an optimal granulometric composition of the charge, which is characterized by an average equivalent diameter: the higher this indicator, the higher the gas permeability of the charge. The value of the surface tension reaches its maximum at a certain moisture content of the charge, which is the optimal moisture for this charge. By increasing the amount of return during agglomeration, the vertical sintering rate increases and the quality of the agglomerate improves. These factors lead to an increase in the productivity of sintering plants. According to the results of the study, the optimal parameters of the sintering sintering process of rolled scale in a mixture with iron-containing steelmaking waste were worked out. It is established that the optimal amount of return is the use of 20 % of the mass of the sintering charge at the optimal height of the sintered layer of 300 mm. As a result of the conducted research, the following optimal indicators were achieved: mechanical strength – 70.2 %, sintering rate – 28.7 mm/min, specific productivity – 1.75 t/m2·hour. Keywords: Rolling scale, agglomeration, optimal parameters, sintering, return, layer height.

Integrating High-Performance Flexible Wires with Strain Sensors for Wearable Human Motion Detection.

Flexible electronics have revolutionized the field by overcoming the rigid limitations of traditional devices, offering superior flexibility and adaptability. Conductive ink performance is crucial, directly impacting the stability of flexible electronics. While metal filler-based inks exhibit excellent conductivity, they often lack mechanical stability. To address this challenge, we present a novel conductive ink utilizing a ternary composite filler system: liquid metal and two micron-sized silver morphologies (particles and flakes). We systematically investigated the influence of filler type, mass ratio, and sintering process parameters on the composite ink's conductivity and mechanical stability. Our results demonstrate that flexible wires fabricated with the liquid metal/micron silver particle/micron silver flake composite filler exhibit remarkable conductivity and exceptional bending stability. Interestingly, increasing the liquid metal content results in a trade-off, compromising conductivity while enhancing mechanical performance. After enduring 5000 bending cycles, the resistance change in wires formulated with a 4:1 mass ratio of micron silver particles to flakes is only half that of wires with a 1:1 ratio. This study further investigates the mechanism governing resistance variations during flexible wire bending. Additionally, we observed a positive correlation between sintering temperature and pressure with the conductivity of flexible wires. The significance of the sintering parameters on conductivity follows a descending order: sintering temperature, sintering pressure, and sintering time. Finally, we demonstrate the practical application of this technology by integrating the composite ink-based flexible wires with conductive polymer-based strain sensors. This combination successfully achieved the detection of human movements, including finger and wrist bending.

Calibration of a constitutive model for polycrystalline diamond sintering process

Polycrystalline diamond is mostly pressed at high temperature in actual production. Thus, circumferential strain data of powder moulding are difficult to collect at high temperatures. As a result, the parameters of DPC constitutive model cannot be obtained using conventional testing methods. Moreover, the use of conventional equipment to test the mechanical properties becomes challenging because of the extremely high hardness and compressive strength of polycrystalline diamond. Sintering tests of polycrystalline diamond were carried out at 1360 °C and 223 Mpa using the spark plasma sintering (SPS) method, and displacement–load data were obtained. The spark plasma sintering experiment of polycrystalline diamond under high temperature and pressure was carried out using the Drucker Prager/Cap (DPC) model with relative density to obtain accurate displacement and load numbers. Combined with USDFLD subroutine, the experiment of polycrystalline diamond sintering was simulated on ABAQUS. Based on the complex method, ABAQUS-MATLAB platform is used for the reverse identification of constitutive parameters. The constitutive model parameters of polycrystalline diamond sintering process are obtained. This approach can describe the mechanical behaviour of polycrystalline diamond powder in the sintering process. In addition, the inverse identification method of the constitutive model in the sintering process of polycrystalline diamond based on ABAQUS and MATLAB solves the problem on the difficulty to observe the sintering of polycrystalline diamond under high temperature and high-pressure environment. Moreover, the constitutive model parameters of the sintering process are obtained, thereby reducing the cost and condition constraints in the actual experiment. A novel technique involves obtaining powder constitutive parameters at high temperature from the sintering point of view. This approach is important to simulate sintering of polycrystalline diamond and its composite products. Foundation itemNational Natural Science Foundation of China (Grant No. 52075438), the Key Research and Development Program of Shanxi Province of China (Grant No. 2020GY-106), the Open Project of State Key Laboratory for Manufacturing Systems Engineering (Grant No. sklms2020010), and the Open Research Fund of Key Laboratory of Oil & Gas Equipment of Ministry of Education (Grant No. OGE201702-110).

Investigation of the effect of sintering process parameters on the corrosion, wear and hardness of W–Cu composite

Investigation of the effect of sintering process parameters on the corrosion, wear and hardness of W–Cu composite

Mechanical properties and thermal shock resistance of TiB2‒B4C composite ceramic tool materials at microscopic scale

AbstractA finite model incorporating microstructure was developed to investigate the thermal shock resistance of TiB2‒B4C composite ceramic cutting tool materials. Numerical simulations were conducted to analyze changes in the transient temperature field and thermal stress field during the thermal shock process. TiB2‒B4C composite ceramic tool materials were fabricated using discharge plasma sintering technology. With different B4C contents, different sintering temperatures and holding times as study variables, optimization of the sintering process parameters and ceramic material components was achieved through testing the mechanical and microscopic morphology of the ceramics. Thermal shock water quenching experiments were performed, and the strength‐decay method was employed to assess the thermal shock resistance of TiB2‒B4C ceramics. The findings indicate that the optimal sintering conditions are temperature of 1700°C and holding time of 5 min. The TiB2‒B4C ceramic material containing 20 vol% B4C exhibits superior comprehensive mechanical properties and thermal shock resistance, and its relative density, fracture toughness, hardness, and flexural strength were 99.3%, 6.8 MPa m1/2, 22.8 GPa, and 598 MPa, respectively. The critical thermal shock temperature difference falls within the range of 400°C‒500°C.

Optuna-DFNN: An Optuna framework driven deep fuzzy neural network for predicting sintering performance in big data

Sintering performance index can reflect the quality of sintered ore, and the level of sintered ore performance directly affects the stability of blast furnace production. Accurate prediction of sinter performance metrics is essential to optimise sinter quality, improve production efficiency and reduce energy consumption. Based on the sintering big data, this paper proposes the Optuna-DFNN model by combining the fuzzy neural network algorithm, the deep neural network algorithm and the Optuna framework to address the problems of difficulty in tuning the parameter, lack of self-learning ability, and poor generalisation of the model of the traditional method when faced with the input of multiple parameters. The paper predicts the four prediction indexes of yield rate, return fines ratio, drum index and RDI+3.15 respectively. Among them, the relative error of the prediction of the yield rate is within 1.3 %, the relative error of the prediction of the return fines ratio is within 2.8 %, the relative error of the prediction of the drum index is within 0.32 %, and the relative error of the prediction of the RDI+3.15 is within 1.4 %. The results indicate that the Optuna-DFNN model has better performance in predicting sintering performance metrics. Based on the Optuna-DFNN sintered ore performance prediction model, the quality of sintered ore can be accurately predicted, the sintering process parameters can be adjusted in a timely manner, the sintering process can be optimized, and the utilization coefficient of sintering can be improved. Provide a reference for the optimisation of production processes, with a positive impact on cost reduction, environmental protection and increased sustainability of production.

An Experimental Investigation of a Flexible Sintered Silver Joint for Micro-Joining Based on a Design of Experiments

The increasing electrification of vehicles requires the use of ever higher voltages and electrical power. The thermal stresses to which the assembly joints of electronic chips are subjected are becoming increasingly severe. As a result, thermal stresses acting on the electronic assembly, and particularly on the electrical interconnections, are becoming increasingly severe. The objective of this study is to create, characterize and optimize the structure and properties of a porous silver sintered joint using the design of experiments (DoE) method. Joints consisting of a porous network of silver particles are obtained, showing remarkable flexibility allowing for thermal stresses accommodation and having sufficient tensile strength to ensure a correct bonding of the components. Depending on the selected levels for the sintering process parameters, the microscopy analysis shows a transition of the mode of rupture from the silver layer to the intermetallic compounds forming at the interface with the substrate.

Optimizing the sintering process parameters for simultaneous improvement of the compression strength, impact strength, hardness and corrosion resistance of W–Cu nanocomposite

The main purpose of this work is to optimize the mechanical properties of tungsten–copper (W–Cu) nanocomposite fabricated by the sintering process. For this purpose, the parameters of sintering temperature, sintering time and weight percentage of copper were selected to optimize the compression strength, impact strength, hardness and corrosion resistance of the W–Cu nanocomposite using the desirability function procedure and response surface method. The analyses of transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) were also performed to examine the microstructure of W–Cu nanocomposite. The results exhibited that a rise in the sintering temperature from 1000∘C to 1150∘C significantly enhanced the impact strength of W–Cu nanocomposite, while a rise in the sintering temperature from 1150∘C to 1300∘C deteriorated the impact strength. Moreover, the compression strength and hardness of the W–Cu nanocomposite continuously improved by elevation of sintering temperature from 1000∘C to 1300∘C. A rise in the amount of Cu from 20[Formula: see text]wt.% to 40[Formula: see text]wt.% led to a reduction in the hardness of the W–Cu nanocomposite, while a rise of Cu content improved the impact and compression strengths. The results also indicated that the mechanical properties of W–Cu nanocomposite enhanced simultaneously by using 27[Formula: see text]wt.% Cu at sintering temperature of 1197∘C and sintering time of 2.7[Formula: see text]h. The samples sintered at the optimal conditions indicated a higher corrosion resistance than that sintered at the initial conditions.

The influence of spark plasma sintering on multiscale mechanical properties of nickel-based composite materials

The paper presents a comprehensive investigation of the influence of the main process parameters of spark plasma sintering on the mechanical and microstructural properties of nickel-silicon carbide composites at various scales. Microstructure analysis performed by scanning and transmission electron microscopy revealed a significant interfacial reaction between nickel and silicon carbide due to the decomposition of silicon carbide. The chemical interaction of the matrix and reinforcement results in the formation of a multicomponent interphase zone formed by silicides (Ni31Si12 or/and Ni3Si) and graphite precipitates. Furthermore, several types of structure defects were observed (mainly nano/micropores at the phase boundaries). These significantly influenced the mechanical response of nickel-silicon carbide composites at different levels. At the macroscopic scale, uniaxial tensile tests confirmed that applying a 1000 °C sintering temperature ensured that the manufactured composite was characterised by satisfactory tensile strength, however, with a considerable reduction of material elongation compared to pure nickel. Moreover, the fractography study allowed us to identify a significant difference in the damage mode for certain nickel-silicon carbide samples. Secondly, the interface of the nickel matrix and silicate interphase was tested by bending with microcantilevers to evaluate its deformation behaviour, strength, and fracture characteristics. It was confirmed that a diffusive kind of interface, such as Ni-NiSi, demonstrates unexpected bonding properties with a relatively large range of plastic deformation. Finally, the nanoindentation of three main components of the nickel-silicon carbide composite was executed to evaluate the evolution of nanohardness, Young's modulus, and elastic recovery due to the application of various spark plasma sintering conditions.

Study on performance and mechanism of foamed ceramics based on lead fuming furnace slag

This paper proposes a new method for preparing lightweight and thermally insulated foamed ceramics via direct high-temperature foaming using lead fuming furnace slag as the major material, quartz sand as the texturizer, borax as the flux, and AlN as the foaming agent. The effects of the chemical composition and sintering process parameters on the crystalline phase transformation, pore structure, and properties of the foamed ceramics were investigated. The foaming mechanism during sintering was also examined using TG-DSC analysis and pore morphology analyses. These results indicate that the slag content strongly affects the formation of the pore structure. Different sintering parameters can modify the pore structure, and a single crystalline phase (CaSiO3) was generated during the sintering process. Under the optimum conditions, the foamed ceramics showed the best overall performance with the bulk density, apparent porosity, average pore size, thermal conductivity, and compressive strength of 0.221 g cm−3, 84.53 %, 1.10 mm, 0.1100 W/(m·K), and 2.52 MPa, respectively. Its excellent porous structure and low thermal conductivity make it suitable as a thermal insulation material in building partition walls.

Three-dimensional modeling of grain structure growth within ceramic tool material

Ceramic cutting tool materials possess specific advantages, including high hardness, excellent wear resistance, and high chemical stability, making them unparalleled in the machining of difficult-to-process materials compared to traditional cutting tools. The mechanical performance of these materials is primarily determined by their microstructure. Therefore, it is necessary to simulate and optimize the microstructure of ceramic cutting tool materials to provide theoretical guidance for further enhancing their fracture toughness. In this paper, a simulation model based on sintering densification theory was proposed, coupling crystal plasticity with a three-dimensional cellular automaton, to investigate the impact of nanoparticle content, sintering temperature, sintering pressure, and holding time on grain growth in composite ceramic materials using spark plasma sintering (SPS). Furthermore, an evolution model for grain growth of TiB2-TiC-SiC nanocomposite ceramic materials in cutting tools is established, and the optimal sintering process parameters are obtained. Finally, SPS experiments were conducted. Under the conditions of a sintering temperature of 1600 °C, holding time of 7 min, and sintering pressure of 40 MPa, optimal mechanical performance composite ceramic cutting tool materials were prepared. The experimental results, including a hardness of 25.6 GPa, fracture toughness of 7.1 MPa·m1/2, and flexural strength of 628.2 MPa, were consistent with the simulation outcomes. This indicates that the designed simulation model for nanocomposite ceramic grain growth reliably reflects the physical process of grain growth in the material and provides valuable guidance for further understanding the mechanisms underlying grain growth.

Investigating laser sintering in Y3Al5O12 ceramics

This study investigates the experimental parameters of the laser sintering process of Y3Al5O12 ceramics. Ceramic powders were produced using the polymeric precursor method and sintered using a CO2 laser as the heating source. The samples were characterized using differential thermal analysis, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy techniques. The results showed that parameters such as powder calcination temperature, dwell time, and laser power density rate are crucial in obtaining dense ceramic bodies. Furthermore, developing and using a sample holder made of the same material composition to be sintered showed significant advances in the laser sintering process.

Influence of Sintering Process Parameters on Properties and Dimensional Accuracy of MIM17-4PH Stainless Steel

Influence of Sintering Process Parameters on Properties and Dimensional Accuracy of MIM17-4PH Stainless Steel

Microstructural and micromechanical characterization of sintered nano-copper bump for flip-chip heterogeneous integration

Copper nanoparticles (CuNPs) sintering for flip-chip interconnects is a promising solution for 3D and heterogeneous integration to overcome the limitation of solder materials. To this end, we perform the photolithographic stencil printing method to pattern CuNPs, and the form of flip-chip interconnects is completed after CuNPs sintering process. This paper aims to study the effect of sintering processing parameters (time, pressure, temperature) on the mechanical properties of CuNPs bumps when applying the novel method to approach the Cu interconnects. We fabricated seven groups of specimens of sintered CuNPs bumps, built with a diameter of 100 μm and sintered. The nanoindentation tests assessed the mechanical property to get Young's modulus and hardness. Results clarify that Young's modulus is strongly affected by pressure. An suggested combination of parameters (the 25 MPa and 260 °C for 15 min) give the highest modulus of 126 GPa and the hardness of 1.76 GPa. Moreover, the observations by scanning electron microscopy (SEM) reveal the microstructure and porosity evolution versus different processing parameters.

Study on the process and microstructure of Fe34Mn13.5Al3Cr7.5Ni alloy prepared by spark plasma sintering based on elemental powder

FeMnAlCrNi shape memory alloy exhibits constant superelasticity over a broad temperature range, which has application prospect in aerospace field. In this paper, Fe34Mn13.5Al3Cr7.5Ni superelastic alloy was prepared by spark plasma sintering, and the effects of pre-sintering and sintering process parameters, element diffusion process, and superelastic properties of the alloy were investigated. The orthogonal experiment was conducted to determine the optimal parameters and laws revealed that the compactness degree and hardness of this sintered alloy reached 99.7 % and 291HV, respectively, which were treated by a process of 620 ℃ and 15 min pre-sintering temperature and time, and final sintering temperature of 1000 ℃ under the sintering pressure 45 MPa. In FeMnAlCrNi alloy with multiple elements and significant differences in their melting points, Al element with low melting point will affect the diffusion and microstructure of alloy elements during sintering. The results show that Al element was in a liquid state during the sintering process, which helps to improve the density of the alloy. The remaining Al element in the alloy generated a small amount of pores due to the Kirkendall effect during heat treatment. After heat treatment, the superelastic recovery of the alloy was 0.46 % under 3 % compression.

Optimization of Sintering Process Parameters by Taguchi Method for Developing Al-CNT-Reinforced Powder Composites

In powder metallurgy, the sintering process is a high-power consuming and critical process for better mechanical properties of composites due to proper diffusion of atoms. In this context, different sintering processes were investigated along with their sintering condition. The present work focused on optimizing conventional sintering process parameters for carbon nanotubes (CNTs) reinforced aluminum composites using Taguchi optimization methods. The Taguchi L9 orthogonal array (OA) experiment was considered for the investigation. CNT’s wt.%, sintering temperature, and time were chosen as process parameters in the sintering process, while macro-hardness and relative density were evaluated as performance evaluation characteristics. The signal-to-noise ratio (S/N) and ANOVA statistical procedures were utilized to evaluate the effect of sintering parameters/levels on the micro-hardness and relative density of the Al/CNTs composite sintered. ANOVA statistical analyses revealed that the CNTs wt.% significantly influences relative density (83.58%), followed by temperature (14.58%), whereas CNTs wt.% significantly influenced micro-hardness (77.75%), followed by temperature (13.64%). The sintering of Al/CNTs composites using these optimum conditions is recommended to reduce power consumption and enhance the quality of the sintered composite.

Optimization of Spark Plasma Sintering Technology by Taguchi Method in the Production of a Wide Range of Materials: Review.

This paper reviews the production of sinters using the spark plasma sintering method. SPS (spark plasma sintering) technology has been used for several decades, mainly in laboratories, to consolidate a huge number of both new and traditional materials. However, it is now more often introduced into practical industrial use, with equipment as early as the fifth generation capable of producing larger-size components at competitive costs. Although the mechanism of sintering with the use of this method is not yet understood, the effectiveness of the SPS process for the rapid and efficient consolidation of a wide range of materials with novel micro-structures remains indisputable. With a relatively wide variation in chemical composition, the structure allows the selection of appropriate consolidation parameters for these materials. The influence on the values of apparent density and mechanical properties depends on the parameters of the spark plasma sintering process. In order to achieve a density close to the theoretical density of sinters, optimization of the sintering parameters, i.e., sintering temperature, heating rate, sintering time, pressing pressure and protective atmosphere, should be carried out. In this paper, the optimization of spark plasma sintering of Si3N4-Al2O3-ZrO2 composite was carried out using the Taguchi method. The effects of four sintering factors, namely heating rate, sintering time, sintering temperature and sintering pressure, on the final density were investigated. Optimal sintering conditions were proposed and a confirmation experiment was conducted. The optimal combination of sintering conditions for spark plasma sintering (SPS) of Si3N4-Al2O3-ZrO2 composite for high apparent density was determined as A3-B3-C3-D2. Based on ANOVA analysis, it was found that the apparent density of sintering was significantly influenced by sintering temperature, followed by pressing pressure, sintering time and heating rate. Validation of the developed mathematical model predicting the apparent density of sinters showed close agreement between the predicted response results and experimental results.

Process optimization of simple preparation of AgNPs by polyol method and performance study of a strain sensor

In this experiment, silver nanoparticles (AgNPs) were prepared by the polyol method, which is simple and low-cost. The AgNPs were characterized by SEM, UV–Vis, and XRD. It was determined that the prepared AgNPs had good morphology and the average particle size was about 53.01 nm. At the same time, the optimum conditions for preparation were determined: The molar ratio of polyvinylpyrrolidone K30 (PVP K-30) to AgNO3 was 6:1, the reaction time was 40 min, and the reaction temperature was 160 °C. Then the sintering process parameters were discussed. It was determined that when the content of AgNPs was 2.5%, the temperature of high-temperature sintering should reach 250 °C and above, the time should reach 30 min and above, and the lowest resistivity reaches 0.7 × 10−5 Ω·m under high-temperature sintering. In chemical sintering, Cl− replaces the N and O atoms of PVP K-30, induces spontaneous aggregation of Ag, and completes room temperature sintering. It is found that the sintering time needs to reach 30 min or more, and the resistivity is 3.325 × 10−5 Ω·m. Finally, the conductive region is printed by the material deposition system and the strain sensor is prepared by two sintering methods. The experimental test proves that the sensor prepared by high-temperature sintering has good cycle response and stability. The sensor prepared by chemical sintering has a good cycle response, but the repeatability is poor, which is not conducive to long-term high-strength use. The sensor can be applied to the field of flexible electronic products.

Light weight- low modulus biocompatible titanium alloys processed via spark plasma sintering

There is a wide range of biomedical applications for titanium and its alloys due to their biological inertness, excellent biocompatibility, superior corrosion resistance, and little to no adverse reactions. However, the commonly used titanium (Ti-6Al-4 V) alloys have been reported to have high elastic modulus (116 GPa) compared to human bone (10–40 GPa), resulting in bone atrophy caused by stress shielding, a phenomenon of bone degradation caused by an insufficient supply of stress from the implant. The presence of aluminum and vanadium in titanium alloys has also been linked to neurodegenerative diseases like Alzheimer's. A new class of titanium biomedical alloys (Ti-35 Nb-7Zr-5Ta (wt%) also referred to as TNZT alloys) with low toxic alloying elements (niobium, tantalum, and zirconium) and capable of combating the problems associated with Ti-6Al-4 V alloys are being developed. In the present study, various physical, structural, mechanical, and biological properties of such TNZT alloys have been explored, along with their relationship to sintering processing parameters such as sintering temperature (400, 600, 800, and 1000 °C) and sintering pressure (20, 40, and 60 MPa). The sample sintered at 1000 °C demonstrated a single β-phase (BCC) of titanium which clearly indicates that selected sintering temperatures preserve the BCC β-phase in titanium without the formation of the HCP α-phase. Both density and elastic modulus of spark plasma sintered (SPS) TNZT samples increased with increasing sintering pressure and temperature, and the underlying mechanisms were discussed. All the sintered TNZT alloys exhibited excellent biocompatibility and have the potential for use as long-lasting and high-performance biomedical materials.