Optimization Of Sintering Process Research Articles

Sintering process optimization of the additively manufactured pure copper parts through the metal paste deposited process

The fabrication process, sintering cycles through two sintering methods, microstructural and texture characterization, mechanical properties, and electrical conductivity of metal paste-deposited copper parts were investigated in this study. In the first condition, samples were air-debinded for carbon content removal followed by a sintering cycle. A sintering profile with the maximum sintering temperature and time of 1080 °C and 1 hr. was implemented after performing the air-debinding cycle at 250 °C for 2 hrs. In the second condition, samples were sintered in the environment of copper oxide for carbon removal in the early stages of the sintering cycle, i.e., 1070 °C for 1 hr and 1080 °C for 1, 2, and 3 hrs. The microstructural observations revealed coarser grains in the air-debinded samples, perhaps due to additional generated heat during carbon oxide formation, which may produce destructive effects on the boundary (HAGBs, twins, and CSL) volume and densification behavior of copper parts. However, through the second method, much finer grains and higher densities of boundaries were detected in the microstructure. Despite the significant effect of sintering conditions on the microstructure, texture interpretations revealed minor changes in the pole figures for different situations. Using the second sintering method and owing to the less carbon content and based on the density of the boundaries and their configurations, higher electrical conductivity (98.4±1.3 % IACS) was recorded by sintering the green parts. The comparison between the data from this study with other parts printed through other additive manufacturing techniques demonstrated a superior electrical conductivity level and acceptable balance between strain and strain notably with the sample sintered for 3 hrs.

Optimization of sintering process to fabricate high-density ultrafine-grained (HfNbTaTiZrW)C ceramic: A comparative study

The fabrication of senary carbide (HfNbTaTiZrW)C was achieved by carbothermal reduction process combined with three different kinds of sintering paths, including conventional single-step sintering (CS) and two kinds of two-step sintering (TSS-1 and TSS-2). It is revealed that the synthesized nanosized powders (∼102 nm) through carbothermal reduction exhibited excellent sintering capability to obtain a high density single-phase solid solution with homogeneous metal cation distributions at macro- and sub-micrometer scales, while atomic-level heterogeneity existed with Zr segregation. Compared to CS samples with bimodal microstructure, the application of two-step sintering significantly reduced the amounts of intergranular pores and (ZrHf)O2, accompanied with grain refinement. In particular, a well-designed TSS-2 route comprising short-term high-temperature followed by low-temperature sintering achieved ultrafine-grained bulk with grain size of 1.44±0.22 μm and excellent mechanical properties of elastic modulus of 480 MPa, microhardness of 23.4 GPa, and fracture toughness of 3.8 MPa·m1/2.

3D extrusion printing of 304 stainless steel/polypropylene composites and sintering process optimization

3D extrusion printing of 304 stainless steel/polypropylene composites and sintering process optimization

Strategies of strengthening mechanical properties in the osteoinductive calcium phosphate bioceramics.

Calcium phosphate (CaP) bioceramics are widely applied in the bone repairing field attributing to their excellent biological properties, especially osteoinductivity. However, their applications in load-bearing or segmental bone defects are severely restricted by the poor mechanical properties. It is generally considered that it is challenging to improve mechanical and biological properties of CaP bioceramics simultaneously. Up to now, various strategies have been developed to enhance mechanical strengths of CaP ceramics, the achievements in recent researches need to be urgently summarized. In this review, the effective and current means of enhancing mechanical properties of CaP ceramics were comprehensively summarized from the perspectives of fine-grain strengthening, second phase strengthening, and sintering process optimization. What's more, the further improvement of mechanical properties for CaP ceramics was prospectively proposed including heat treatment and biomimetic. Therefore, this review put forward the direction about how to compatibly improve mechanical properties of CaP ceramics, which can provide data and ideas for expanding the range of their clinical applications.

Binder Jet 3D Printing of 316L Stainless Steel: Orthogonal Printing and Sintering Process Optimization

Binder jet 3D printing (BJ3DP) is an additive manufacturing technique that uses a liquid binder to selectively deposit powder layer by layer to fabricate 3D parts followed by sintering. Herein, the printing parameters, sintering temperature, and holding time of 316L stainless steel (SS) materials produced by BJ3DP technique are systematically investigated. Based on the L9 orthogonal experimental design, the green parts can achieve the highest relative density of ≈55.9%, when the layer thickness, binder saturation, and roller traverse speed are 150 μm, 35%, and 100 mm s−1, respectively. Five green parts printed using the optimal parameters are subsequently sintered under different temperatures and holding time. All the as‐sintered samples consist of a primary γ‐Fe phase and a small amount of δ‐ferrite phase. After sintering at 1435 °C for 7.5 h, the as‐sintered samples obtain the highest relative density of ≈92.1% along with the most excellent mechanical properties, displaying ultimate tensile strength of ≈558 MPa and an elongation of ≈41%. The mechanical properties of these samples sintered at 1435 °C for 7.5 h are also superior to those of the annealed 316L SS in ASTM A276/A276M‐17.

Simulation and Experimental Study of the Multisized Silver Nanoparticles Sintering Process Based on Molecular Dynamics.

Multisized nanoparticles (MPs) are widely employed as electronic materials to form conductive patterns, benefitting from their excellent sintering properties and mechanical reliability. However, due to the lack of effective detection methods for the real-time sintering process, it is difficult to reveal the sintering behavior during the MPs sintering process. In this work, a molecular dynamics method is used to track the trajectory of silver atoms. The melting behavior of a single nanoparticle (SP) is first discussed. The structural evolution of equally sized nanoparticles (EPs) and unequally sized nanoparticles (UPs) during the sintering process is analyzed alongside morphology changes. It is proposed that the UPs sintering process benefits from the wetting behavior of small-sized nanoparticles on the surface of large-sized nanoparticles, and the sintering angle (θ) is proposed as an index to estimate the sintering result of UPs. Based on the works above, three basic sintering modes and one advanced sintering mode in the MP sintering process are analyzed emphatically in this paper, and the roles of different-sized nanoparticles in MPs are concluded from simulation and experimental results. This work provides theoretical support for conductive ink composition design and sintering process optimization.

Optimization of sintering process and enhanced hybrid improper ferroelectricity of Ca3Ti2O7 ceramics fabricated by an acetic acid sol–gel method

Optimization of sintering process and enhanced hybrid improper ferroelectricity of Ca3Ti2O7 ceramics fabricated by an acetic acid sol–gel method

Silver Sintering for Silicon Carbide Die Attach: Process Optimization and Structural Modeling

The increasing demand in automotive markets is leading the semiconductor industries to develop high-performance and highly reliable power devices. Silicon carbide MOSFET chips are replacing silicon-based solutions through their improved electric and thermal capabilities. In order to support the development of these novel semiconductors, packaging technologies are evolving to provide enough reliable products. Silver sintering is one of the most promising technologies for die attach. Due to their superior reliability properties with respect to conventional soft solder compounds, dedicated reliability flow and physical analyses should be designed and employed for sintering process optimization and durability assessment. This paper proposes an experimental methodology to optimize the pressure value applied during the silver sintering manufacturing of a silicon carbide power MOSFET molded package. The evaluation of the best pressure value is based on scanning electron microscopy performed after a liquid-to-liquid thermal shock reliability test. Furthermore, the sintering layer degradation is monitored during durability stress by scanning the acoustic microscopy and electric measurement of a temperature sensitive electric parameter. Moreover, mechanical elastoplastic behavior is characterized by uniaxial tensile test for a bulk sample and finite element analysis is developed to predict the mechanical behavior as a function of void fraction inside sintering layer.

Optimization of Sintering Process of Alumina Ceramics Using Response Surface Methodology

In this work, alumina (Al2O3) ceramics were prepared using an environmentally friendly slip casting method. To this end, highly concentrated (70 wt.%) aqueous suspensions of alumina (Al2O3) were prepared with different amounts of the ammonium salt of a polycarboxylic acid, Dolapix CE 64, as an electrosteric dispersant. The stability of highly concentrated Al2O3 aqueous suspensions was monitored by viscosity measurements. Green bodies (ceramics before sintering) were obtained by pouring the stable Al2O3 aqueous suspensions into dry porous plaster molds. The obtained Al2O3 ceramic green bodies were sintered in the electric furnace. Analysis of the effect of three sintering parameters (sintering temperature, heating rate and holding time) on the density of alumina ceramics was performed using the response surface methodology (RSM), based on experimental data obtained according to Box–Behnken experimental design, using the software Design-Expert. From the statistical analysis, linear and nonlinear models with added first-order interaction were developed for prediction and optimization of density-dependent variables: sintering temperature, heating rate and holding time.

Qualitative and Quantitative Microstructural Analysis of Copper for Sintering Process Optimization in Additive Manufacturing Applications

Abstract This work will present possibilities for the characterization of copper powder green bodies and sintered copper microstructures during pressureless sintering. The introduction of new parameters to microstructural characterization based on qualitative and quantitative microstructural analysis will facilitate the systematic optimization of the sintering process. As a result of the specific evaluation of the microstructure evolution, conventional isothermal sintering could be successfully replaced by multi-step temperature profiles, thus achieving sintering densities of more than 99 % by simultaneously reducing process time. This systematic optimization of the sintering process of Cu through specific microstructural analysis may now be applied to sinter-based manufacturing technologies such as Binder Jetting and Metal Powder Injection Moulding, enabling the manufacture of complex and highly conductive Cu parts for applications in electronics.

Sintering Process Optimization for 3YSZ Ceramic 3D-Printed Objects Manufactured by Stereolithography.

A 3YSZ (3 mol% yttria-stabilized zirconia) ceramic green body with 50 vol% of ceramic content was 3D-printed by supportless stereolithography under optimal drying, debinding, and sintering conditions in order to achieve high strength and density. The viscosity and flowability of the ceramic nanocomposite resins were optimized by adjusting the amounts of non-reactive diluents. The ceramic 3D-printed objects have a high polymer content compared to ceramics samples manufactured by conventional manufacturing processes, and the attraction between layers is weak because of the layer-by-layer additive method. This causes problems such as layer separation and cracking due to internal stress generated when materials such as solvents and polymers are separated from the objects during the drying and debinding processes; therefore, the drying and debinding conditions of 3YSZ ceramic 3D-printed objects were optimized based on thermogravimetry–differential thermal analysis. The sintering conditions at various temperatures and times were analyzed using X-ray diffraction, SEM, and flexural strength analysis, and the body of the 3YSZ ceramic 3D-printed object that sintered at 1450 °C for 150 min had a relative density of 99.95% and flexural strength of 1008.5 MPa. This study widens the possibility of manufacturing ceramic 3D-printed objects with complex shapes, remarkable strength, and unique functionality, enabling their application in various industrial fields.

Fabrication of multifilamentary powder in tube superconducting tapes of Bi-2223 with Sr deficient starting composition

Bi2SrxCa2Cu3O10+δ (Bi-2223) precursor powders were fabricated by co-precipitation process with different Sr content of x = 1.93, 1.90, and 1.85. Multi-filamentary Bi-2223 high temperature superconducting tapes were fabricated by the traditional powder in tube process (PIT) with different precursor powders. The influences of Sr content on the phase formation dynamics as well as the superconducting properties of Bi-2223 tapes have been systematically investigated. With decreasing Sr content, the critical temperature of Bi-2223 tapes decreased from 109.9 K to 107.7 K, which implied that the change of Sr content could change the carrier concentration on Cu-O plane, thus led to the variation of intrinsic superconducting transition behavior. Besides, with the decrease of Sr content, the phase formation temperature decreased. Bi-2223 tapes with higher superconducting phase content were obtained with the Sr content of 1.85, which was beneficial to the improvement of intergrain connections. Thus, the Jc-B behavior was enhanced under the magnetic field parallel to the ab plane of Bi-2223. With further optimization of sintering process, the maximum Ic of 128 A was achieved on Sr = 1.85 tape, corresponding to the critical current density, Jc of ~ 25.8 kAcm−2.

Optimization of sintering process on Li1+xAlxTi2-x(PO4)3 solid electrolytes for all-solid-state lithium-ion batteries

In this study, a NASICON-structured Li1.3Al0.3Ti1.7(PO4)3 (LATP) powder is prepared by hydrothermal methods followed by calcination, cold pressing and post-sintering processes. The white, solid product is characterized thoroughly using powder X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) equipped with Energy Dispersive X-ray Spectroscopy (EDS). The conductivity of the material is measured by a impedance spectroscopy as a function of temperature. Initially, hydrothermal synthesis yields a material isostructural with the orthorhombic oxyphosphate, LiTiOPO4. EDS analysis shows that the distribution of aluminum throughout this material is uniform. A systematic study is then performed to investigate how altering the sintering parameters (such as powder pre-sintering temperature and pellet sintering temperature) affect the formation of LATP. The structure is determined by Rietveld refinement against XRD data and the effects of sintering temperature on porosity, microstructure and electrical conductivity were resolved. The experimental results show that the optimum pre-sintering and sintering temperatures of LATP powders and pellets respectively are 900 °C and 1100 °C. These conditions produce materials with the highest density (99.07% of theoretical), superior conductivity (grain-, grain boundary- and total lithium-ion conductivities of 6.57 × 10−4, 4.59 × 10−4 and 2.70 × 10−4 S cm−1, respectively) and with an activation energy for Li motion of 0.17 eV.

Improving Transport Properties of Bi-2223 Superconducting Tapes With the Optimization of Packing Atmosphere

Multifilamentary Bi2Sr2Ca2Cu3O10+δ (Bi-2223) high temperature superconducting tapes were fabricated by powder-in-tube process. During the precursor powder packing process, environment atmosphere was changed from pure oxygen to dry air and 7.5% O2 balanced with N2, with the oxygen partial pressure decreasing from 100% to 25% and 7.5%, respectively. The change of packing atmosphere obviously influenced the phase assemblage in the early stage of Bi-2223 phase formation process. Therefore, the chemical composition of obtained Bi-2223 phase as well as the content and distribution of secondary phases changed accordingly. Meanwhile, the changes of intergrain connections and the flux pinning properties were investigated based on the in-field critical current, $I_{c}$ – B measurements. Finally, attributed to the decreased oxygen partial pressure in packing atmosphere, the $I_{c}$ improvements of 25% at self-field and 0.6 T were obtained comparing with the tapes packed under pure oxygen. With further optimization of sintering process, the final $I_{c}$ of 116 A was achieved, which corresponded to the critical current density, $J_{c}$ of ∼21 kAcm−2.

Laser sintering process optimization of microstrip antenna fabricated by inkjet printing with silver-based MOD ink

Inkjet printing has been widely used for the manufacturing of patch antennas, circuit boards, biochemical sensors, frequency selection surfaces and other electronic devices. As an essential process, laser sintering is of great significance to the inkjet printing, which can enable the printed patterns to possess very good conductivity. The laser sintering process for the MOD (Metal Organic Decomposition) ink is investigated in this manuscript. First of all, the laser sintering simulation of the MOD ink is carried out based on COMSOL Multiphysics and change mechanism of the sintering temperature under different process parameters is revealed. Then, sintering experiments and process optimization are conducted on the self-developed platform, and the sintering quality differences are comparatively analyzed by measuring the widths, conductivities and thicknesses of the printed silver lines. Finally, a microstrip antenna is fabricated based on the optimized process and the performance of the manufactured antenna satisfies the use requirements. The simulation results are highly consistent with the experimental results, and both of them have verified the feasibility, reliability and effectiveness of the optimized sintering process.

Fabrication of conformal array patch antenna using silver nanoink printing and flash light sintering

The sintering process constitutes an important part of the conductive-pattern inkjet printing process, as it directly affects the conductivity of the conductive pattern. Flash sintering has significant advantages such as lower processing temperature and higher sintering efficiency than other existing processes. Multiple flash sintering process experiments were performed to solve the problems of low conductivity of the sample caused by unsuitable concentrations of nano-silver ink and flash sintering process parameters. The relationship model between the nano-silver ink parameters and the flash sintering process parameters was established. The sintering neck state of the nanoparticles under different sintering parameters was observed by scanning electron microscope, which revealed the flash sintering mechanism of the nano-silver. A non-contact sintering effect monitoring method and a sintering process optimization method are also proposed. A microstrip array antenna was fabricated based on this method. The effectiveness and feasibility of the proposed method are proved by simulation and experimentation of the antenna pattern.

Exergy Analysis and Optimization of Sintering Process

Iron ore sintering is an important and large energy‐consumption segment in the iron and steel industry. It is thus essential to save energy in the sintering process considering both quality and quantity. This paper takes exergy loss minimization as an optimization objective, and a sintering optimization model is established based on material balance and exergy balance. Optimized results are obtained by solving constrained multidimensional nonlinear programming problems. Two types of sintering processes, in which solid fuels consist of coke and coke/coal powder, are calculated and analyzed. The effects of fuel ratio, fuel preheat temperature, and sinter basicity on exergy losses are also studied. The results show that the exergy losses obtained from optimizations for two types of solid fuels decrease by 5.0% and 8.1%, respectively. Exergy loss has a negative correlation with the coal ratio and fuel preheat temperature and a positive correlation with the coke ratio and sinter basicity. Exergy efficiencies increase from 29.7% to 35.0% and 35.5%, for each optimization. The research in this paper is highly significant to exploring of the sintering process, guiding steel production, and reducing energy consumption.

Nanoparticle‐Based Cu2ZnSn(S,Se)4 Solar Cells With a 9.1% Efficiency Obtained by an Optimization of Sintering Process

The sintering process of Cu2ZnSn(S,Se)4 (CZTSSe) films coated on Mo substrates is optimized by using a selenium/sulfur mixture atmosphere and a designed graphite box. Structural characterization indicates that this optimization is advantageous in reducing the thickness of high resistance Mo(S,Se)2 layer. In addition, Cu content contained in the CdS layer is significantly decreased compared with that obtained by the selenium sintering. An active area efficiency of 9.1% CZTSSe solar cell (without anti‐reflective coating and light soaking) is achieved, demonstrating that the improvement of the Mo/CZTSSe and CZTSSe/CdS interfaces leads to an increased conversion efficiency.

Thermal Stress Analysis of Powder Metallurgy Sintering Process Based on ANSYS

Powder metallurgy is a technology process that the powder is pressed and sintered to get the metal and composite products. The sintering temperature is one of the main technology parameters of pressing sintering. In significant measure, the sintering temperature determines the organization and geometry size of the material, which directly affects the performance of the material. This paper takes magnesium powder metallurgy sintering material as the research object, studying the transient thermal analysis with the ANSYS finite element software, systematic researching the sinter temperature field and thermal stress field of sintered body in the sintering process, and observing in the corresponding distribution of stress field and deformation under different sintering temperature distribution graph. Temperature field and thermal stress field are the main factors affecting the quality of the sintered body in sintering process. Uneven temperature distribution will cause larger thermal stress. When the thermal stress exceeds a certain limit, the sample will be deformed. With the temperature increases, the sintering temperature difference increases, the stress distribution in the constantly changes. The stress and deformation is not entirely visible for sintered body, the deformation and cracking will be side by side in the sintering process. Therefore, theory of temperature field and thermal stress distribution are studied and discussed in certain sintering processing, the sintering process optimization can be designed to provide quantitative basis of the theoretical analysis.

Enhanced apatite precipitation on a biopolymer-coated bioactive glass

AbstractIn this work, sintered pellets of a silica-based bioactive glass were dip-coated with a biocompatible natural-derived polymer in order to investigate the influence of the organic coating on the glass bioactivity. After the sintering process optimization, uncoated and coated pellets have been characterized by means of scanning electron microscopy with energy dispersive spectroscopy (SEM, EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and pH measurements, after the immersion in a simulated body fluid (SBF). An increased apatite forming ability and a better control of the pH during soaking of the samples in SBF were observed in the presence of the biopolymer. This result opens a new insight on the simple fabrication of highly bioactive hybrid inorganic-organic materials for medical applications.