Papers by Keyword: Cold Isostatic Pressing (CIP)

Abstract: The microstructure and mechanical properties of zirconia toughened alumina (ZTA) ceramic added with niobia (Nb₂O₅) through cold isostatic pressing (CIP) method was investigated. The amount of Nb₂O₅ is varied from 0 wt.% to 7 wt.%. The phase composition of the sintered bodies was analyzed with an x-ray diffractometer, while their microstructure was observed with a scanning electron microscope. It is found that up to 3 wt.% of Nb₂O₅ addition, the secondary phase of Nb₂Zr₆O₁₇ presence as square shape particles confirm by SEM and EDX. The addition of 3 wt.% showed the highest Vickers hardness value with 1600HV. It was observed that, further addition of Nb₂O₅ (> 3 wt.% ) deteriorates the Vickers hardness of ZTA. While the fracture toughness value increased at 3 wt.% until 5 wt.% of Nb₂O₅ addition (6.71 MPa · √m and 6.80 MPa · √m respectively). It was also found that the value for bulk density increased and porosity decreased with the increasing of Nb₂O₅ addition.

Abstract: The amorphous nano-sized silicon nitride powders were sintered by cold isostatic pressing –normal press sintering method. The sintering additives of Y2O3 and Al2O3 powders with average grain size less than 20nm were prepared by polyacrylamide gel method. Relative density of sintered materials rise and pore size reduce with increasing of cold isostatic pressing. When the pressure is 100MPa, the density is only 48% and average pores size is between 2μm and 20μm which obvious the first particle space. When the pressure is 200MPa, the density is 67% and agglomerated particle size reduce obviously as well as the pores size are between 0.1μm and 1.0μm which appears because of the second particle. Pressed compact with a relative density 74% and average pore size less than 0.5μm reach to a good density state at 300MPa pressure. Sintering material composites with Si2N2O and β-Si3N4 phases, compared with hot press sintering composites, which indicates that increasing of sintering press is conducive to the formation phase Si2N2O. Relative density is above 96% and average pore size is less than 500nm at sintering temperature 1800°C.

Abstract: The article main discusses the development, production and application of directional multi -microtubule purging plugs which used in large or medium sized bottom blowing converter. This type of purging plug makes the gas flow in the metal pipes with very small resisting force and good air tightness. It is produced by using cold isostatic pressing, and has high strength and good corrosion resistance. Mainly employed high purity fused magnesia, flake graphite as raw material, and used phenolic resin as binder, and added titanium carbide, boron carbide as antioxidants and additives, which improved anti-oxidation, corrosion resistance and washing resistance, and the life of purging plug is highly improved accordingly.

Abstract: Recycling glass is chosen as an alternative raw material in upgrading ceramic into glass ceramic. The main objectives are to determine the effect of sintering temperature and the recycled glass to ball clay weight ratio on glass ceramic produced from recycled glass. The recycled glass powders are prepared by crushing and grinding waste glass bottles to a particles size distribution below than 75 µm. The raw materials (recycled glass powder and ball clay) are characterised by Differential Thermal Analysis (DTA) and its composition is determine by X-Ray Fluorescence (XRF). The recycled glass powder are then mixed with the ball clay according to the ratio of SLSG to ball clay of 95:5 wt.%, 90:10 wt.% and 85:15 wt.%. Green samples of glass ceramic are then fabricated using Cold Isostatic Pressing (CIP) with constant pressure at 40 MPa. Sintering process is conducted at three different temperatures at 750°C, 850°C and 950°C with 1 h holding time. The sintered glass ceramic were then characterised using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses. Results of physical analyses and microhardness testing conducted according to ASTM C 373 and ASTM C 1327 showed that better properties is achieved at batch composition compromised of 85:15 wt.% ratio of recycling glass to ball clay and sintered at 850 °C. SEM micrographs showed that samples produced from this optimum batch composition provide more homogeneous and dense surface. Furthermore, XRD analysis indicates that crystalline phases evolved during sintering contributes to the final strength of the glass ceramic. These encourage further development on the glass ceramic samples which intended for structural applications.

Abstract: In our previous studies, 10-40wt%Ni/Al2O3 membrane was prepared by uniaxial pressing and sintered at 900 to 1400°C for 2 h. It was found that 10wt%Ni/Al2O3 membrane sintered at 1400°C showed the highest physical and mechanical properties. Thus, this work we focused on the effect of different pressing processes on the properties of Ni/Al2O3 membrane with longer soaking time. Firstly, 10-40wt%Ni and Al2O3 powders were mixed by dried ball-milling. Then, the mixture powder was pressed to form a bar shape by two different processes; uniaxially pressing (No CIP) and uniaxially pressing followed by cold isostatic pressing (CIP) at 250 MPa for 5 min. All Ni/Al2O3 specimens from two pressing routes were sintered at 1400°C for 4h under air atmosphere and reduced at 900 °C under H2 (99.99%). From the results, it was found that the densification process affected to physical and mechanical properties of Ni/Al2O3. The CIPed - 10wt%Ni/Al2O3 membrane sintered at 1400°C for 4 h showed the highest relative density and flexural strength of 76% and 106 MPa with the lowest pore size (78 nm) and 17% porosity. The addition of nickel content gradually decreased physical and mechanical properties of Ni/Al2O3.

Abstract: Selective Laser Sintering could manufacture high complex metal parts in short time but with high porosity and low strength. The components from Cold Isostatic Pressing have excellent performance with uniform organizational structure, high size precision, and high density. It, however, could not form high complex parts because of the difficulties of bag manufacture. So it will be a good method to combine Selective Laser Sintering and Cold Isostatic Pressing to make complicated metal parts. In this paper, the specimens of stainless steel were made by the combined Selective Laser Sintering and Cold Isostatic Pressing forming route. And the simulation of Cold Isostatic Pressing was carried out by finite element method and Drucker-Prager-Cap constitutive model in ABAQUS/Explicit computer program. The property of metal powder was measured by experiments. The effects of bag on Cold Isostatic Pressing have been discussed. It is different from the Cold Isostatic Pressing of metal powder that the bag has little influence on both shape and size of the specimen. The results of simulation show a good agreement between the experimental results and the calculated results. The simulation can give a useful direction to dimension and shape designs of the combined forming of Selective Laser Sintering and Cold Isostatic Pressing.

Abstract: Investigations carried out referred to obtaining material based on the high-speed steel and non-alloy steel. The conventional powder metallurgy method was used for manufacturing these materials, consisting in compacting the powder in the closed die and sintering it next, the isostatic pressing method, and the modern pressureless forming powder metallurgy. Forming methods were developed during the investigations for high-speed and non-alloy steel powders, making it possible to obtain materials with three layers in their structure. Investigations included determining the sintering conditions, and especially the temperature and treatment cycle, as well as examining the selected mechanical properties. It was found out, basing on the comparison of structures and properties of test pieces made with the pressureless forming method, as well as with the isostatic pressing and pressing in the closed die, with further sintering, that in structures of all examined test pieces in the sintered state fine carbides occurred distributed homogeneously in the high-speed steel layer. It was noticed, that increase of the sintering temperature, regardless of the manufacturing method, results in the uncontrolled growth and coagulation of the primary carbides and melting up to forming of eutectics in layers consisting of the high-speed steel. It was found out basing on the microhardness tests that hardness of test pieces both those pressureless formed, compacted in the closed die, and isostatically cold pressed and sintered grows along with the sintering temperature. It was also noted that the sintering temperature range is bigger in case of the pressureless formed materials.