Structure and Properties of Mixed Former Aluminum Borate Glasses Modified With Silver Oxide

The current study focuses on glass preparation and characterization in the xAl2O3 (35-x) Ag2O.65B2O3 system (0≤x≤35 mol%), where Ag2O is replaced with Al2O3. To examine a wide range of both structure and morphology of the produced glasses, nuclear magnetic resonance (NMR) of 27Al nuclei, X-ray diffraction (XRD) spectroscopy, and transmission electron microscopy (TEM) are used. Changing the Al2O3 and Ag2O molar ratios reveals a substantial change in material structure. In Al2O3-rich glass, the well-formed AlO6, AlO5, and AlO4 structured groups are the well-formed units. In samples of (20 and 30 mol % Al2O3), tetrahedral AlO4 and traces from AlO6 units may be detected. At lower concentrations of Al2O3 (10 mol%), the dominant unit is only AlO4 groups containing non-bridging oxygen bonds (NBO). The XRD and EDP spectra confirm the amorphous nature of the glasses of Al2O3 ˂ 20 mol%. Glasses of higher Al2O3 concentrations contain crystalline Ag2Al2B2O7 which are formed due to the higher oxygen packaging of the mixed AlO5 and AlO4 compared with that of glasses containing only AlO4 species. The amount of higher coordinated Al species AlO5 and AlO6 are gradually increased in response to an increase in the ratios of Al2O3/Ag2O. The morphology of crystalline units is confirmed from TEM to differ from that of an amorphous composition. The conductivity decreases and the activation energy for ionic conduction increase with increasing Al2O3. The hardness number of the studied glasses is highly increased with increasing Al2O3 content. The increase of activation energy and the hardness number of the glasses led to an increase in the durability of the investigated glasses.

Effect of pack carburizing with chicken egg shell powder agent and vibrator quenching on the mechanical properties of AISI 9310 steel

The effects of vibrator quenching (QV) on the carbon content, microstructure, and mechanical properties (surface hardness number, wear resistance) in the pack carburizing of AISI 9310 steel were studied. The aim of this research is to increase the surface hardness and improve the wear resistance of AISI 9310 steel. The problem that often occurs in the quenching treatment after pack carburizing is that the thick cooling medium does not evenly wet the surface of the specimen, so that the cooling rate is not uniform, the impact is the distribution of the specimen surface hardness is not the same. Therefore, it is necessary to research the implementation of the vibrator in the quenching treatment. The specimens were treated with pack carburizing at a temperature of 875 °C, soaking time for 3 hours. The carburizing agent consisted of chicken egg shell powder (CESP) and rice husk charcoal (RHC) with various weight ratios of 5 %:95 %, 15 %:85 %, and 30 %:70 %. Followed by quenching treatment using a 10 % cane molasses cooling medium and vibrator. Hardness testing was carried out using a Vickers microhardness tester, wear resistance test using the pin-on-disc method, and a scanning electron microscope (SEM-EDX) was used to observe changes in the microstructure and carbon elemental content on the specimen surface. The results showed that the application of VQ caused the formation of a small martensite microstructure while without VQ it was large martensite and a few of residual ferrite. The highest surface hardness number is 685 kg/mm2, the wear resistance is 0.32 cm/mg for pack carburizing, using carburizing agent 70 % RHC, 30 % CESP and VQ. VQ causes a more even distribution of the thick cane molasses cooling medium so that the cooling rate of the specimens is uniform.

Evaluation of Vickers Hardness Number of Al-Si Alloy Under Heat Treated Conditions

The paper deal with the hardness property assessment of various Al-Si alloys under heat treated conditions. The tested specimens have the compositions of Si with percentages such as 12 18 and 24. The fabrication of the selected composition is carried out by melting the material to the melting temperature of around 800°C. The material is subjected to solutionised heat treatment for 3 hours at 500°C, 520°C and 535°C and quenched in water. Further aging is carried out at 155°C for 2 hours, 5 hours and 8 hours respectively for 500°C, 520°C and 535°C of solution heat treatment condition. The hardness property is evaluated using Vickers Hardness tester as per the standards of ASTM- E92. Thorough comparison of Vickers hardness number is performed among the as- cast and various heat treated environment. Desirable properties of alloy are observed at 520°C solutionised heat treatment & 5 hours of precipitation hardening at 155°C for 18% of Silicon composition. The hardness value decreases due to the increase in percentage of silicon and the values are observed.

A study of the pack carburizing quenching treatment with cane molasses cooling medium effect on the wear resistance of low carbon steel

In the present study, various quenching media were added as cooling media for the quenching after pack carburizing treatment. The aim of this research is to get a suitable cooling medium for pack carburizing quenching treatment to increase the wear resistance of low carbon steel. Many cylindrical specimens for the adhesion wear tests were prepared from the used SS400 steel according to ASTM G99-04 specifications. Two heat treatment processes, namely pack carburizing and quenching were done. Firstly, the specimens are pack-carburized at a temperature of 875 °C, soaking time of 2 hours and quenched. The carburizing agent consists of Pinctada maxima shell powder (PMSP) and corn cob charcoal with a weight ratio of 30:70 %. Different cooling media (water, 10 % NaCl solution, 10 % cane molasses) in the pack carburizing quenching treatment are subjected to different kinds of tests. The hardness test was performed using Vickers micro hardness tester, the wear resistance was used in adhesive wear test, the carbon content was determined and microstructure examination was made using a scanning electron microscope (SEM-EDX). The result showed that all cooling media contributed to an increase in mechanical properties (surface hardness number, wear resistance), carbon content and microstructure change. The use of cooling media in the pack carburizing quenching process generally increases the surface hardness number of the specimen. The highest surface hardness number was 595 kg/mm2, respectively using 10 % cane molasses. The work shows that cane molasses can be used as a cooling medium for pack carburizing quenching of SS400 steel and contributed to the improvement of wear resistance

Optimization of Mild Steel Welding Process Parameters Using Multivariate Linear Regression

Local welders in Nigeria are prone to poor quality weldment because of their lack of welding technical skills. When these local welders carry out their welding operation, the welded joints are considered to be good enough because the metal materials welded together are seen to be good and satisfactory. In most case, when these welded joints have not fully served their service life, these materials fail due to the poor quality of the weldment. Material quality can easily be assessed by inspecting the microstructure of the weldment. In this wok, mild steel welding process parameters were optimized using multivariate linear regression (MLR). The study involves the determination of the suitable set of conditions for the welding process parameters that would give the optimum weld of mild steel (low carbon steel) using Gas Metal Arc welding (GMAW) technique and obtain a relationship between the three welding process parameters and the ultimate tensile strength and Brinell hardness number. For this reason, an experimental study was carried out using nine samples of the specimen of mild steel. The experimental and predicted results show that arc voltage and gas flow rate affect the ultimate tensile strength and the Brinell hardness number of mild steel. The maximum ultimate tensile strength and Brinell hardness number were obtained at 180A, 15V and 20l/min. It was also observed that the ultimate tensile strength decreases with increases in arc voltage and gas flow rate. But these two parameters tend to have a positive effect on the Brinell hardness number.

Mechanical Test of Aluminum-Zirconium-Silicate Composite Prototype with Filler Volume Variation

Recently, ceramic material has become a main object of scientific interest especially in dental material. The advance of dental materials technology has led to use of zirconia-based ceramics for composite filler. In this study, composite filler has been synthesized from natural zircon sand through geopolymerization method. Composite prototype were made with different filler volume to evaluate mechanical properties including hardness number and diametral tensile strength. Samples divided into two groups with 50 wt% filler volume (group A) and 75 wt% filler volume (group B) which 3 samples for each group. The surface micro hardness of each group tested by Leco M-400-H1 vickers microhardness testing machine and for diametral tensile strength tested using universal testing machine (Lloyd) with crosshead speed of 1,0 ± 0,25 mm/min. The data were analyzed using independent sample t-test. The results showed that the average of hardness number on group A was 13,8 VHN while for group B was 24,1 VHN. The average of diametral tensile strength for group A was 20,461 MPa and 27,689 MPa for group B. Statistical result showed that the value (P<0,05). The conclusion, there is a signifficant difference on the result of hardness test between group A (50 wt% filler volume) and group B (75 wt% filler volume) and also on diametral tensile strength test.

Improving the surface hardness number of subsoil plow chisel using water-jet preening

This study discusses the effects of pressure in waterjet peening (WJP) of subsoil plow chise. It was made from austenitic stainless steel 301 JIS standard S30100. Analysis of surface integrity and change of surface hardness number is used to evaluate the performance of various parameters in the WJP process. The article summarizes information about austenitic stainless steel physically-mechanical of subsoil plow chisel that is most useful for soil tillage. The subsoil chisel was given surface treatment WJP process with a variation of pressure and time. The physical properties of subsoil plow chisel from various pressure and time of WJP are analyzed. The findings of this study indicated that surface treatment with waterjet peening could increase the surface hardness number and the hardening layer fromaustenitic stainless steel 301 (material of subsoil plow chisel).Treats the surface with WJP pressure 250 MPa and time 3 hours results in a higher increase in surface hardness number up to 41% and 151% greater than the raw material respectively. Also, a deeper hardening layer to depth 250 and 500 μm each produced. Next, the cross-sectional micro structure shows the density is higher than the slip band in the defective grain of specimens that have undergone the WJP process at the time and higher pressure. However, the number of slip bands in grain defects decreases with the pressure drop.