Effect Of Sintering Parameters Research Articles

Effect of Sintering Parameters and Liquid Phase Content on the Properties of Fe-Rich Based Impregnated Diamond Bit Matrix

Effect of Sintering Parameters and Liquid Phase Content on the Properties of Fe-Rich Based Impregnated Diamond Bit Matrix

Effects of sintering parameters on the preparation and properties of foamed ceramics from cyanide tailings

ABSTRACT In this study, foamed ceramics were successfully prepared using cyanide tailings (CTs) with a high sulfur content as the main raw material. The effects of sintering temperature, holding time, and heating rate on the bulk density, water absorption, porosity, pore structure, and compressive strength of foamed ceramics were systematically investigated. The results showed that the elevated sintering temperature promoted the generation of liquid phases, resulting in an obvious enlargement of the pore size and a decrease in bulk density. In addition, a similar evolution trend could be found in the pore size and bulk density with the extension of the holding time, which was attributed to the degrees of silicon carbide reaction. Foamed ceramics with small pore sizes could be prepared at a heating rate that did not exceed 4°C/min. Then, the higher heating rates could bring abnormally large pores and be detrimental to the mechanical properties of the foamed ceramics, which were proven to be related to the decomposition of FeS2 introduced by CTs during the heating process. In conclusion, the foamed ceramics prepared with CTs in this study provide effective solid waste utilization and have good application prospects in wall composite one-piece insulation panels.

Tailoring the microstructure of Al/Ti laminated composite through hot press sintering process to achieve superior mechanical properties

A novel method based on hot press sintering was proposed to fabricate the Al/Ti laminated composite, and the effects of sintering parameters on microstructure, interfacial structure, and mechanical properties were thoughtful examined. The results showed that insufficient sintering caused obvious voids and cracks at Al/Ti interface. With the increase of temperature or holding time, a good metallurgical bonding without defects was achieved, and both the recrystallization fraction and grain size of α phase in Ti layer increased, accompanied by the transformation of α to β phase and growth of intermetallic phase. The microstructure variation of Al layer is not evident with changing the sintering parameters. Due to the relatively low formation energy, the nanoscale TiAl3 phase with massive stacking faults formed at Al/Ti interface, and lots of dislocations existed at Al layer near the interface. The voids and cracks formed at Al/Ti interface led to the premature failure of laminate. On the basis of the metallurgical bonding and small TiAl3 phase, the high fraction and texture intensity of α phase were the dominated strengthening factors. Moreover, the back stress generated at Al/Ti interface contributes to an extra strengthening. The superior mechanical properties of Al/Ti laminate with a tensile strength of 670.9 MPa and a fracture strain of 0.33 were obtained with the sintering temperature of 600 °C and holding time of 2 h.

Cr3C2 assisted ultrafast high-temperature sintering of TiC

The strong covalent bonding of TiC renders its densification through conventional sintering difficult. Here, we propose a method involving liquid-phase-assisted ultrafast high-temperature sintering (UHS) for obtaining nearly full density of TiC ceramics by the addition of Cr3C2. The samples were heated at a rate of 600 °C/min to 2200 °C and held at this temperature for 1 min. The effects of sintering parameters and the Cr3C2 content on the relative density and microstructure of the sintered samples were investigated. The main causes of rapid densification were particle rearrangement associated with the Cr3C2 liquid phase, dissolution-reprecipitation associated with the solid solution, and the weak evaporation of Cr formed during UHS. In particular, the addition of Cr3C2 helped increase the hardness and elastic modulus of TiC significantly. This paper presents an effective and extensible method involving UHS for rapidly obtaining dense ceramics.

Effect of sintering parameters on phase evolution, microstructural development and mechanical behavior of Ni46Al12Co18Cr8Fe12Mo4 high entropy alloy synthesized via mechanical alloying and spark plasma sintering

The aim of this research work was to study phase evolution, microstructural development and resulting mechanical properties in Ni46Al12Co18Cr8Fe12Mo4, at. % high entropy alloys (HEAs) synthesized via spark plasma sintering (SPS) of 50 hr mechanically alloyed (MAed) powder with varied sintering parameters. Detailed microstructural analysis of the consolidated samples revealed that sintering at 1100 °C resulted in improved densification, i.e. up to 99% and enhanced grain growth compared to the samples sintered at lower temperatures. Phase analysis of the sintered HEAs envisaged formation of face centered cubic (FCC) structured single-phase solid solution with minor amount of brittle sigma (σ) phases. Phase diagram generated from Thermo-Calc shows that volume fraction of the σ phases decreases continuously with temperature and further they dissolve at 1180 °C, which is in close agreement with experimental results of differential thermal analysis (DTA) performed on the sintered samples. Moreover, microhardness of the consolidated HEAs decreased gradually with increase in sintering temperature, ascribed to lower volume fraction of the brittle σ phases at higher temperature. Further, nanoindentation test was conducted to estimate the hardness of the individual phases and it was found that nanohardness of σ phase is approximately 1.7 times higher than that of the solid solution phase. The HEA sintered at 1100 °C showed an excellent strength-ductility synergy, with a compressive yield strength of 1121 ± 21 MPa and the elongation to failure up to 20 ± 1%, attributed to the presence of ductile FCC phase with minor amount of brittle σ phase. The present study demonstrates the potential of SPS technique to synthesize Ni base HEA with excellent thermal stability and superior mechanical properties for structural applications.

NiTiCu alloy from elemental and alloyed powders using vat photopolymerization additive manufacturing

The metal vat photopolymerization technique (MVP) has high potential for metal part production because of its high accuracy, speed, and flexibility. However, low density, poor mechanical properties, and effects of sintering parameters on the properties are some of the challenges in MVP. This paper is the first to investigate the possibility of producing a NiTiCu metal alloy using VP from Ni, Ti, and Cu elemental and mechanically alloyed powders. The effect of particle size distribution and solid content on the physical and mechanical properties is also studied and compared. The results indicate that all three elements are homogeneously distributed in the whole print without premixing the powders, which considerably reduces processing time. Finer particle size and higher solid content also improve densification degree, hardness, flexural strength, and surface quality of the final parts. The measured surface roughness (Ra) of NiTiCu was 6.42 µm and 10.31 µm for milled and elemental powders, respectively. However, the mechanical properties of NiTiCu produced by VP in this study remain insufficient and in need of further improvement.

Effect of Sintering Parameters on the Mechanical Properties and Wear Performance of Alumina Inserts

The sintering temperature and holding time have a significant impact on the densification of a ceramic compact. In this study, alumina inserts were made with varying sintering temperatures and holding times. The procedure began with the compacting of alumina powders inside a mould with trapezium and round shapes. These inserts were then sintered between 1200 °C and 1400 °C for 5 to 9 h holding time. The sintered samples underwent analysis based on the shrinkage size, density, and microstructure. The sample with the highest density was chosen for additional machining tests. The results showed that the alumina shrinkage ranged from 3 to 6%, with a maximum relative density of 91.3% recorded when the sintering parameter was applied at 1400 °C and a 9 h holding time. The transition of the grain growth was observed depending on the sintering temperature and heating duration. When machined with AISI 1045 carbon steel, the sintered alumina inserts achieved a maximum tool life of 35 s at a cutting speed of 350 m/min. The sintered inserts exhibited brittle characteristics with a dominant notch wear and abrasive mechanisms.

Effect of Sintering Parameters on Microstructural Evolution of Low Sintered Geopolymer Based on Kaolin and Ground-Granulated Blast-Furnace Slag

The effect of different sintering parameters on the mechanical properties of sintered kaolin-GGBS will influence the variation of mechanical properties of sintered kaolin-GGBS geopolymer. Based on previous research, the samples have major cracking and many large pores due to the sintering temperature and holding time during the sintering process. The first objective is to study the effect of different sintering parameters on the mechanical properties of sintered kaolin-GGBS geopolymer and the second objective is to correlate the strength properties of sintered kaolin-GGBS geopolymer with microstructural analysis. In a solid-to-liquid 2:1 ratio, kaolin and GGBS were combined with an alkali activator. The kaolin-GGBS geopolymer was then cured at room temperature for 24 h. The samples were then cured for 14 days at 60 °C, followed by using double-step sintering at temperatures of 500 °C and 900 °C with varying heating rates and holding durations. The compressive strength and shrinkage of the kaolin-GGBS geopolymer were evaluated, and the morphology was examined using a scanning electron microscope. In comparison to other samples, the sintered kaolin-GGBS geopolymer with a heating rate of 2 °C and a holding duration of 2 h had the optimum compressive strength value: 22.32 MPa. This is due to the contribution of MgO from GGBS that refines the pore and increases the strength. The 13.72% shrinkage with a densified microstructure was also obtained at this parameter due to effective particle rearrangement during sintering.

Effect of sintering parameters on the microstructure and micromechanical properties of in-situ synthesized boride phases (Fe2B-FeB) in iron matrix composites reinforced with B4C particles

In this study, the influence of sintering parameters on the microstructure and micromechanical properties of ceramic reinforced iron matrix composites is investigated. Composites containing 5–10-20-30 vol% B 4 C were fabricated by in-situ powder metallurgy (IPM) and sintered at various temperatures and durations. Hot pressed powder mixtures were sintered at constant duration (60 min at 1000–1150-1300 °C) and constant temperature (1150 °C for 30–120 min) in a protective environment. The influence of these parameters is evaluated by investigating microstructural changes using SEM, XRD, EDX, and optical microscopy, density and porosity by Archimedes method, and finally, micromechanical properties by hardness determination. Results showed that while increasing reinforcement ratios of B 4 C particles caused reduced density in the green compacts, B 4 C particles under a certain size (<7 μm) were randomly distributed in the mixture and lead to the formation of iron borides. Additionally, increased hardness was witnessed for all temperatures with increasing reinforcement ratios until 20 vol% B 4 C, after which hardness was decreased. In fact, 20 vol% B 4 C showed excellent properties and was comparatively much sensitive to both, increasing sintering temperatures and duration. In-situ synthesized iron borides became the decisive factor in the increased hardness of the composites. • The properties of Fe-B 4 C composites were evaluated at various sintering parameters. • The iron boride phase was formed in different sizes and shapes as a result of the diffusion of boron from the B 4 C. • Composition of mixture powders and sintering time affected the dispersion of the boride phase. • The hardness of composites was significantly developed by in-situ synthesized boride phases. • Sintering time causes the phase formation in larger areas that enhanced the overall hardness.

Effects of Sintering Parameters on the Low-Temperature Densification of GDC Electrolyte Based on an Orthogonal Experiment

A solid oxide fuel cell is a high-efficiency power device in hydrogen energy utilization. The durability and dynamic performance of metal-supported solid oxide fuel cells (MS-SOFCs) are superior to those of electrolyte- or electrode-supported cells, with many potential applications. Gadolinium-doped cerium (GDC) has a high oxygen ionic conductivity, making it suitable to act as the electrolyte in MS-SOFCs operating at 500–650 °C. However, the low-temperature sintering of GDC is difficult for MS-SOFCs. In this study, the factors affecting the low-temperature densification of GDC are analyzed based on an orthogonal experimental method. The shrinking rates of 16 experiments are determined. The effects of the particle diameter, pressure of the uniaxial press machine, sintering temperature, and fractions of aid and binder are estimated. The results of a range analysis indicate that the content of sintering aid has the greatest impact on the low-temperature densification of GDC, followed by the powder diameter and the uniaxial pressure. A maximum shrinking rate of 46.99% is achieved with a temperature of 1050 °C.

Novel Ti–Si–C composites for SOFC interconnect materials: Production optimization

This paper presents a first part of research of designing a new Ti–Si–C-based composite for potential application as a solid oxide fuel cells interconnect material. Spark plasma sintering technique was used for the production and the effects of sintering parameters on microstructure, phase composition, as well as mechanical and electrical properties were investigated. Optimization of the sintering conditions then allowed to obtain a fine-grained material with properties (bending strength 433 MPa, hardness of 9.6 GPa, electrical resistance 26 mΩ cm) surpassing those of Crofer steels, materials typically used in the SOFC interconnect applications nowadays. This is a very promising result, yielding our Ti–Si–C composite a serious candidate for new-generation lightweight interconnect materials.

Production of B4C reinforced TZM alloy and boriding its surface in one step by spark plasma sintering (SPS)

TZM alloy is one of the most important Mo-based alloys that has been used for high temperature applications due to its high melting point, good thermal conductivity and low thermal expansion coefficient. However, low oxidation resistance at elevated temperatures limits the high temperature applications of TZM. In this study, B4C reinforced TZM alloy was produced and its surface was borided in one step with spark plasma sintering (SPS) method. Homogeneously mixed TZM + B4C powders were molded between B4C powders and both sintering and boriding process were performed in a single step at different pressure and holding times. The effects of sintering parameters on densification, phase formation, microstructure, hardness and oxidation behavior were investigated. The thickness of the MoB based protective layers varied from 215 to 430 μm depending on holding time and pressure. Boride layer of all samples had a lower hardness value than the matrix due to porosity formation near the surface. The hardness of the boride layers varied from 5.1 to 16.1 GPa depending on the amount of porosity. The highest hardness value was measured as 17.2 GPa on the matrix of TZM5B-10-70. Mo2B-Mo2C based matrix formation and MoB based protective layer improved the oxidation resistance of TZM alloy by reducing mass loss caused by exposed Mo.

The effects of cold sintering parameters on the densification of Na2WO4 ceramics using Na2WO4·2H2O dry powders

AbstractCold sintering process (CSP) combines transient liquid phase and/or external pressure to assist the densification of ceramics, the sintering mechanism of which is typically dominated by the “dissolution–precipitation” process. In this work, Na2WO4·2H2O dry powders without liquid water have been used as the “liquid phase” to realize the densification of Na2WO4 ceramics. The effects of sintering parameters on the CSP of Na2WO4 ceramics using Na2WO4·2H2O dry powders are systematically studied, including sintering temperature, external pressure, sintering process time and the amount of Na2WO4·2H2O phase. It is found that the “liquid phase,” that is, Na2WO4·2H2O is the key factor for controlling the CSP of Na2WO4 ceramics, and Na2WO4·2H2O hydrate shows an advantage of homogeneous dispersion of liquid water. The sintering temperature affects the densification mechanism involved with plastic deformation and the “dissolution–precipitation,” external pressure accelerates the densification process, and enough sintering process time ensures the completion of CSP. Finally, the optimum cold sintering parameters of Na2WO4 ceramics by Na2WO4·2H2O powders are obtained at 150°C and 240 MPa for 60 min with a pretreatment at 150°C for 30 min.

EXPERIMENTAL INVESTIGATION OF WELD JOINTS BETWEEN SINTERED NB MODIFIED HK30 STAINLESS STEEL AND WROUGHT/CAST STAINLESS STEELS

Very important property of powder metallurgy parts is ability to join to components produced by different manufacturing technologies or dissimilar materials. Properties of powder metallurgy Nb modified HK30 components are highly influenced by conditions applied during sintering. Weldability of sintered components can be improved using favorable sintering conditions. In this regard, effect of sintering parameters on fusion weldability of Nb modified HK30 is presented in this paper. Investigation of weld joints between HK30, produced by different sintering conditions, and cast HK30 stainless steel is performed. In addition, examination of welds between sintered HK30 and wrought 304 stainless steel is also performed. Microstructural examination and hardness testing of fusion zones and heat affected zones were done for different combinations of base material.

Microstructure features of high performance soft magnetic alloy Fe-3 wt.% Si prepared by metal injection molding

The effects of sintering parameters and microstructure features on magnetic properties of Fe-3 wt.% Si alloy prepared by metal injection molding (MIM) was investigated in this study. The sample with high density, the saturation induction (Bs) of 2.0 T, maximum permeability (μmax) of 25 mH/m, coercivity of 22.4 A/m was obtained at 1300 °C for 4 h in hydrogen atmosphere, and the properties of which are close to that of high silicon steel. The microstructure, impurities of C and O, distribution of grain boundary angles and magnetic domain of the sintered alloys were analyzed in correlation with the magnetic properties. It is found that a suitable large grain size of about 300 μm and large grain boundary angles distributed in the range of 30°–60° are beneficial to soft magnetic properties. Moreover, uniform and broad magnetic domains also play an important role in preparation of high performance soft magnetic materials.

Investigation of the properties and leaching characteristics of ceramic cores fabricated using BaZrO3 as the raw material

BaZrO3 ceramic cores were fabricated successfully by pressureless sintering. Effects of sintering parameters on properties and leaching characteristics of BaZrO3 ceramic cores were investigated carefully. When the holding time was constant, with the increase of sintering temperature, the linear shrinkage, bulk density and bending strength of BaZrO3 ceramic cores all gradually increased, but the apparent porosity gradually decreased. At the same sintering temperature, as the holding time increased from 0.5 h to 2 h, the linear shrinkage, bulk density and bending strength of BaZrO3 ceramic cores showed an increasing trend, while the apparent porosity exhibited an opposite trend. By further extending the holding time, the properties of ceramic cores were not significantly improved. Additionally, the prepared BaZrO3 ceramic cores showed excellent leaching characteristics in the boiled acid solution. Especially, for the BaZrO3 ceramic cores prepared at 1500 °C with 2 h, the leaching rate could reach the max value of 50%/h.

Electrochemical behavior of various grade P/M stainless steels processed by rapid microwave hybrid sintering (super-solidus) method

Three categories of stainless steel P/M samples were prepared using the microwave hybrid heating method at super-solidus state temperature (1300 °C). The effect of sintering parameters on pore morphologies and electrochemical behavior of the samples were analysed with different holding time. The electrochemical/electrical characteristics were derived from the PDP/EIS measurements and it has shown an increase in passive film capability with the holding time. The 316L, 430L and 410 have exhibited 37%, 23% and 53% decrement respectively in corrosion rate upon increasing holding time from 30 to 60 min. A parameter active area factor deduces from EIS measurements is decreased by 6–18 times. The variation in corrosion morphologies for three grades of stainless steel is characterized through E-MAP analysis.

Highly oriented α-Al2O3 transparent ceramics shaped by shear force

Alumina platelets were arranged horizontally in submicron alumina particles by shear force in the flow of slurries during casting. The obtained alumina green bodies with platelets were pressureless-sintered in vacuum, producing ceramics with thoroughly oriented grains and high transmittance. The effects of sintering parameters on the densification, microstructure evolution, and orientation degree of alumina ceramics were investigated and discussed. The results showed that the densification, grain size, orientation degree, and in-line transmittance were increased with increasing sintering temperature. The enhancement of orientation degree was mainly coherent with grain growth. The grain-oriented samples exhibited a much higher in-line transmittance (at 600 nm) of 61 % than that of the grain random sample (29 %). Moreover, the transmission remained a high level in the ultraviolet range (<300 nm).

Formation of Yttria Aluminium Garnet by Microwave Sintering

Polycrystalline yttrium aluminium garnet (YAG) ceramic has been prepared using microwave sintering. Micron-sized of Al2O3 and Y2O3 powders were mixed through in house fabrication mixer for 24 hours before calcined at 1100 °C and palletization process. The effect of sintering parameters on the microstructures was observed at various and holding times. X-ray diffraction (XRD) analysis was carried out to determine and quantify phase transformation with respect to these parameters. It was found that three phases namely YAM (Y4Al2O9), YAP (YAlO3) and YAG have been identified. While both grain sizes and density of sintered samples were found increased from 1.4 μm to 2.46 μm and 90% to 98%, respectively. Therefore, microwave sintering has a significant effect on the densification behavior of YAG.

Effects of Sintering Parameters and WC Addition on Properties of Iron-Nickel Pre-Alloy Matrix Diamond Composites

The impregnated diamond composites are widely used for rock drilling and the processing of construction materials. In order to decrease the sintering temperature so as to reduce the thermal damage of diamond, and ultimately improve the sharpness of the diamond tool, the iron-nickel pre-alloyed powder sintered specimens and the impregnated diamond composites were prepared by powder metallurgy. The microstructure and phase composition of specimens were characterized by SEM and EDS. The effect of sintering temperature and the content of WC particles on the mechanical properties of the specimens, such as relative density, hardness, bending strength and wear resistance were investigated. The results showed that the relative density, hardness and bending strength of the sintered specimens increased first and then decreased with the sintering temperature changing from 700 °C to 900 °C. The performance of the specimens sintered at 800 °C was the best, with the corresponding values of 97.75%, 24.0 HRC and 2114.87 MPa. The optimum content of WC was 30wt%, and the grinding ratio reached to 424.11. The rate of penetration of drilling bits with iron-nickel pre-alloyed based matrix increased by 91.14% compared with the traditional bits which used 663Cu-Co-Ni-Mn as binder.