Effect of Input Parameter of Cold Isostatic Press (CIP) Towards Properties of Zirconia Block

Zirconia have become widely studied as consequence of their outstanding mechanical properties, such as hardness, mechanical strength and fracture toughness, which allow them to cover a wide spectrum of applications as structural ceramics, including the field of biomaterials. This study was to compare the strength properties of zirconia block with and without Cold Isostatic Press (CIP). The mechanical properties of zirconia block with and without CIP were characterized. Samples of zirconia block will undergo forming process via Cold Isostatic Pressing (CIP), four levels of soaking time (no CIP, 60, 90 and 120 minutes). All of the sample with different soaking time then were sinter in the furnace. The parameter for sintering process was fixed 1300ºC at rate of 3ºC / min. All of the sample were tested for its strength properties using Vickers test. The density and shrinkage of the zirconia block was be analyzed. Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) were used to characterize samples if zirconia blocks.

The Effect of the Addition of Y2O3 on the Microstructure of Polycrystalline Alumina Ceramics

In the scope of this study, a powder mixture was prepared that contained 3 Al2O3-Y2O3 consisting of 99.99% pure Al2O3 and aluminum oxide of 65–67% and 70% by weight of 99.999% pure Y2O3 powders. After the powders were weighed on a precision scale, the milling process was carried out in a vibratory disc mill. For the granulation, 3 powder mixtures that were subject to sintering were sieved to a size of less than 106 µm in a powder sieve shaker. The powders were shaped with a cold isostatic press after this step and the 3 acquired samples were sintered for 12 h under a temperature of 1923 K. Selected physical and mechanical behaviors were taken by evaluating microhardness measurements, bending strength XRD analysis and electron microscope images of the 3 sintered samples. The changes in the Y2O3 additive and phase composition, microstructure, and mechanic properties were examined.

Effects of Particle Sizes and Natural Polymers on Mechanical Properties of Alpha Tricalcium Phosphate Cements

ABSTRACTCalcium phosphate cements show self-hardening reaction upon mixing with liquids to form calcium-deficient hydroxyapatite (CDHA) or dicalcium phosphate dihydrate. The effects of particle sizes, crystallinities, and natural polymers such as tilapia scale collagen (Col) and hyaluronic acid as a dispersant on the mechanical properties of alpha tricalcium phosphate (TCP) cements mixed with citric acid (CA) as an additive were investigated. Three types of alpha TCP particles were fabricated with spray-dry (SD; 14 μm), freeze-dry (FD; 45 μm), and cold isostatic press (CIP; 134 μm) methods, followed by sintering at 1300°C and ground/crushed. The amounts of Ca dissolution from these particles were in the order of SD > FD > CIP. The CA liquid was added to the powders of SD-FD or SD-CIP, and kneaded under different liquid/powder ratios. The cements containing CIP particles showed lower compressive strength at 22.9 ± 1.5 MPa than those containing FD particles at 28.3 ± 2.5 MPa, even though the apparent densities of the cements containing CIP material was higher. Although the packing density of powders is an important factor on the mechanical properties of cements, the dissolution of Ca ion has a greater impact on the mechanical properties. The addition of Col into the cements increased the mechanical properties at 33.6 ± 2.5 MPa at 1 day to enhance the re-precipitation of CDHA.

Fabrication of Bioactive Polylactic Acid Composite Formed by 3D Printer

We precipitated Apatite Nucleus (AN) by raising pH of SBF. We mixed various concentration of AN in polylactic acid (PLA) and pressed by uniaxial press and cold isostatic press. We investigated the effect of AN concentration on bioactivity. We fabricated composite of PLA and AN configurating the shape by using 3D printer. The composite showed high bioactivity.

The Characterization of Alumina Reinforced with CNT by the Mechanical Alloying Method

Carbon nano tube(CNT) possesses excellent electrical, mechanical and thermal properties. Therefore, it has been applied in a variety of fields. In this study, we added CNT in Al2O3 to improve the characteristics. The composite of CNT(1.5 wt%), Al2O3(∅=20nm), zirconia(90g) and ethanol(20ml) is deconcentrated with planetary ball mill for 1hr, 3hr, 5hr under 200rpm, 300rpm, respectively. The prepared powder was pressed under 14MPa uniaxialy after the composite was dried in the oven at 90°C, and then the powder is pressed again by Cold Isostatic Press(CIP) with 200MPa. Then reinforced alumina matrix composites with CNT was sintered by high temperature furnace at 1525 °C

In Vitro Bioactivity of a Biocomposite Fabricated from Ti and Mg Powders by Powder Metallurgy Method

This study sought to create a biocomposite of Magnesium and Titanium via a powder metallurgy technique. Powder metallurgy technique was used to produce three different volume percentages of Magnesium (30% , 35% , 40%). Titanium powder was mixed with Magnesium, then the samples were compressed by 1800 Bar using a cold, isostatic press process. The samples were then sintered to 850 for 100 min. At this temperature, the compressive yield strength was increased to 210 Mpa and significantly depended on the volume percent of Magnesium present, the core size and temperature of sintering. The bioactivity of the samples in a simulated body fluid (SBF) was also investigated. When the samples were immersed in the simulated body fluid for a 14 and 28 days, calcium and other elements were found to be deposited on the surface. Additionally, it was found that TiO2 has the ability to induce the formation of bone-like apatite in the SBF. In addition, the degradation product of Magnesium in a biological system caused a rise in the pH and environment for the deposition of calcium and other element on the surface were enhanced. Finally, the samples were analyzed using XRD, EDS, and optical and scanning electron microscopy (SEM).

Reduction of Sintering Temperature of Porous Tungsten Skeleton Used for Production of W-Cu Composites by Ultra High Compaction Pressure of Tungsten Powder

Production of tungsten-copper composites includes compaction and sintering of tungsten powder, then infiltration of copper melt within the tungsten skeleton. Sintering of tungsten compacts usually requires a temperature range of 1800 to 2200°C. This means, this process not only needs advanced heating equipments and high expenses but also may cause formation of defects such as structural heterogeneities, cracks and distortions. In this research the required sintering temperature was reduced to 1500°C by increasing compaction pressure. Also the relation between compaction pressure applied through a cold isostatic press (CIP), and green density of the compacted tungsten powder was established. In addition, the effect of various pressures on densification of tungsten compacts during sintering at moderate temperature, i.e. 1500°C was studied, and the optimum structure for infiltration was chosen. Then by infiltrating Cu melt into the optimized W-skeleton, composites of W-Cu having a density of 17.2 gr/cm3 were produced. This method of production provides an innovative technique for obtaining a desired density of infiltrable skeleton, sinterable at a lower temperature than the temperatures used for the conventionally packed W-compacts without introducing structural inhomogeneities during sintering. Study of some characteristics of the optimized composite produced by the above technique satisfied the requirements for production of W-Cu composites having all the specifications given for these types of composites produced at higher temperatures than 1500°C.