This study aims to investigate the relationship between wear resistance and microstructure of a hardfacing alloy Fe-C-Si-Cr-B-Ni system as well as investigating ways of improving the hardness of the hard facing layer through the addition of nickel to achieve a finer granular microstructure. Three hardfacing alloys are used for overlaying. Ferroboron (FeB) and Ferronickel(FeNi), are added to the massive wire during the welding process. A hardness test, microscopic characterization and wear analysis are carried out on the samples. The surfaces of the samples are examined using scanning electron micsoscope in order to better understand the wear mechanism. At room temperature, wear occurs through a combination of abrasive grooving and local delamination. Microstructure and hardness affect the wear resistance of the alloys. Test results shows that as hardness increases, wear resistance increases.

Abstract:In this study, we report the production of β˝-Al2O3 solid electrolyte by using Seydişehir α-Al2O3. Alumina has to be low grain-sized to ensure α-β phase transformation. Therefore, grain refining process was applied to high grain sized Seydişehir alumina by jetmill grinding. Seydişehir alumina was calcined at 1200 0 C for 2 hours. After calcination, calcined Al2O3 and Na2CO3 were mixed during 2 hours in the mill. The samples were pressed and sintered to obtain β˝-Al2O3. β˝-Al2O3 was obtained after sintering at 1550°C for 1 hour. Due to the formation of β˝-Al2O3, it is observed that dielectric properties increased.

In this study, Al2O3-CNT nanocomposites were sintered at 800–1000 °C under 5 GPa for 10 minutes using two different powders as starting material, γ-Al2O3 and AlOOH, respectively. The effect of transition alumina powders on the properties of the high pressure sintered Al2O3-CNT nanocomposites were studied. Al2O3 ceramics have been widely used for structural, electrical, and optical applications. Carbon nanotubes (CNTs) have recently been considered as reinforcing elements in ceramic matrix composites due to their unique mechanical properties. Reactive pressure sintering at low temperatures took place during the fabrication of CNT reinforced ceramic composites to avoid the agglomeration of carbon nanotubes. The hardness and densities were investigated and correlated with the microstructure of the dense materials. SEM analysis was used to determine the CNT distribution in the matrix, the morphology, and size of the particles.

In this study, alumina ceramics were produced with high density and nanograin size without additives from nano-size γ-Al2O3. The effects of sintering pressure (3 GPa and 7 GPa) and temperature (600 °C and 1 200 °C) on the grain size of sintered samples were studied. It was shown that high pressure increases the nucleation rate while reducing the growth rate of the transformed α phase. Pressure-assisted densification decreases grain size, so that nano-scale grains can be achieved in the sintered structure. The effect of various sintering conditions on grain growth in alumina was investigated during high-pressure sintering for better understanding of pressure and temperature effects on microstructural properties.

In the present work, Si3N4-based composites were characterized by a relatively low friction coefficient in unlubricated sliding against a 100Cr6 steel ball. Si3N4-based composites containing different amounts of SiC were produced by spark plasma sintering at 1650 °C for 5 min with a uniaxial pressure of 40 MPa in a nitrogen atmosphere. In the wear test, the load, total distance and rotating speed were selected as 60 N, 120 m and 500 rpm, respectively. The wear tracks were examined by scanning electron microscopy (SEM) to estimate the wear mechanism. The results were evaluated using the friction coefficient-distance diagram. Si3N4-based composites showed significant decrement in wear by improving toughness with SiC powder reinforcement.