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.

STUDY ON THE EFFECT OF COMPOSITION AND VARIATION OF Sn/Zn COOLING MEDIA ON NICKEL ALLOY STEEL THROUGH HOT FORGING AND AUSTEMPERING

STUDY ON THE EFFECT OF COMPOSITION AND VARIATION OF Sn/Zn COOLING MEDIA ON NICKEL ALLOY STEEL THROUGH HOT FORGING AND AUSTEMPERING. Laterite steel with nickel content is expected to be a solution to overcome the lack of domestic steel availability and dependence on imports. This research was conducted to develop Nickel-Chromium-Molybdenum alloy steel used Grinding ball for cement industrial applications. Grinding ball is the one of imported steel products needed to be crushing and size reduction the ores or cement. In addition to import issues, grinding balls have a significant problem: their mechanical properties that do not meet SNI 1049 require the material to have a minimum hardness value of 45 HRC. In this study, the characteristics of Nickel alloy steel were investigated further through heat treatment of forgings heated at the austenitizing temperature of 950 °C and austempering with variations in the cooling medium of Sn/Zn solution. The cooling medium was chosen because it has a melting temperature in the phase diagram area to form the bainite microstructure with complex and challenging characteristics, both of which are required in material for grinding ball applications. In particular, the hardness value that passed the SNI 1069 standard was the use of samples with a Cr-Mo alloy of 1%-wt with a hardness value of 45.92 HRC for Sn Austemper and 48.07 HRC for Zn austemper.

Modifikasi Kotak Polistiren untuk Penyimpanan Dingin Sayur Kubis dengan Menggunakan Es Kering sebagai Media Pendingin

ABSTRAK Penelitian telah dilakukan pada kotak modifypolystyrene sebagai kotak pengiriman kubis segar menggunakan es kering sebagai media pendingin. Penelitian ini bertujuan untuk menguji kotak yang dimodifikasi untuk mengetahui kotak yang paling cocok dimodifikasi untuk menjaga kesegaran sayuran. Kotak polystyrene yang dimodifikasi dibuat dengan memisahkan kotak menjadi dua kompartemen, satu kompartemen untuk menempatkan es kering sebagai media pendingin, dan kompartemen lain untuk menyimpan kubis segar. Itu dibuat lima jenis kotak dimodifikasi, dua jenis media pendinginan mondar-mandir di bawah sayuran segar, sedangkan jenis sisanya menempatkan media pendingin di atas sayuran. Tes yang dilakukan selama 7 jam terdiri dari suhu di sekitar kotak, suhu di dalam kotak, dan suhu pusat kubis segar. Pengukuran lain yang dilakukan adalah berat es kering yang digunakan selama penyimpanan dingin, penurunan berat kubis segar, pengamatan visual kerusakan kubis segar, dan perhitungan keseimbangan energi. Menempatkan es kering di bawah kubis segar menyebabkan suhu tengah kubis segar jauh di atas suhu penyimpanan yang disarankan, 0oC, sementara menempatkan media pendingin di atas sayuran memberi dampak negatif pada sayuran di mana suhu tengah kubis segar di bawah 0oC untuk dua jenis kotak yang dimodifikasi, kecuali es kering yang ditempatkan di baskom yang terbuat dari piring zink. Berdasarkan perhitungan energi, terungkap bahwa hampir lebih dari 75% energi pendingin digunakan untuk mengatasi beban pendinginan di sekitarnya. Ditemukan bahwa kotak modifikasi yang paling cocok untuk menyimpan kubis segar adalah jenis kelima. ABSTRACT Research had been carried out to modify polystyrene box as fresh cabbage delivery box using dry ice as a cooling medium. The research aims were to find out the most suitable model box to maintain the freshness of the vegetables. Modified polystyrene box was made by separating the box into two compartments, one compartment for placing dry ice, and another compartment for storing the fresh cabbage. The box was modified into five types which consisted of two types of the box where the cooling medium was placed below the fresh vegetable, while for the rest, the cooling medium was placed above the vegetable. The tests were performed for 7 hours with the hourly observation that consisted of the temperature surrounding the model box, temperature inside the box, and temperature of the center of the fresh cabbage. Other conducted measurements were the weight of dry ice used during cold storage, weight loss of fresh cabbage, visual observation on the deterioration of the fresh cabbage, and energy equilibrium calculation. Placing dry ice below the fresh cabbage caused the center temperature of the fresh cabbage to far above the recommended storing temperature, 0oC, while placing the cooling medium above the vegetable gave a negative impact on the vegetable where the center temperature of the fresh cabbage was below 0oC for the two types of model boxes, except for the fifth type box where dry ice was placed in a basin made of zink plate. Based on energy calculation it was revealed that almost more than 75% of cooling energy was used to overcome the surrounding cooling load. It was found that the most suitable model box for storing the fresh cabbage was the fifth type.

Experimental Study on a Ceramic Membrane Condenser with Air Medium for Water and Waste Heat Recovery from Flue Gas

Ceramic membrane condensers that are used for water and waste heat recovery from flue gas have the dual effects of saving water resources and improving energy efficiency. However, most ceramic membrane condensers use water as the cooling medium, which can obtain a higher water recovery flux, but the waste heat temperature is lower, which is difficult to use. This paper proposes to use the secondary boiler air as the cooling medium, build a ceramic membrane condenser with negative pressure air to recover water and waste heat from the flue gas, and analyze the transfer characteristics of flue gas water and waste heat in the membrane condenser. Based on the experimental results, it is technically feasible for the ceramic membrane condenser to use negative pressure air as the cooling medium. The flue gas temperature has the most obvious influence on the water and heat transfer characteristics. The waste heat recovery is dominated by latent heat of water vapor, accounting for 80% or above. The negative pressure air outlet temperature of the ceramic membrane condenser can reach 50.5 °C, and it is in a supersaturated state. The research content of this article provides a new idea for the water and waste heat recovery from flue gas.

Ultra-Low Temperature Chillers for Semiconductor Manufacturing Process

The growth of the semiconductor market and advancement of manufacturing technology have led to an increase in wafer size and highly integrated semiconductor devices. The temperature of the supplied cooling medium from the chiller that removes the heat produced in the semiconductor manufacturing process is required to be at a lower level because of the high integration. The Joule-Thomson cooling cycle, which uses a mixed refrigerant (MR) to produce the cooling medium at a level of −100°C required for the semiconductor process, has recently gained attention. When a MR is used, the chiller’s performance is heavily influenced by the composition and proportions of the refrigerant charged to the chiller system. Therefore, this paper introduces a cooling cycle that uses an MR to achieve the required low temperature of −100°C in the semiconductor manufacturing process and provides the results of simple experiments to determine the effects of different MR compositions.

Optimization of Modelling of storage conditions in forced Air cooling of SAPOTA (MANILKARAZAPOTA) using Response Surface Methodology

Field heat can cause rapid deterioration of horticultural crops and therefore it is desirable to remove this heat as quickly as possible after harvesting, and the faster the deteriorative processes are retarded. Thegoal of the present study was to apply Response surface methodology (RSM) to search for the best conditions of Forced Air-Cooling system for extending the shelf life of Sapota.The parameters which affect the cooling rate the most were identified as Cooling Medium temperature (4 ̊C, 8 ̊C and 25 ̊C), Fruit Size (0.00454 m, 0.00567m and 0.00662 m) andCooling Air Velocity (0.5 m/s, 1.5 m/s and 2.5 m/s) at which the produce is stored. Based on general factorial design of RSM shelf life (number of days) as a response, 27 (33) treatments were conducted.Optimum storage conditions for maximizing the shelf life wereidentified as Cooling Medium temperature (4 ̊C), Fruit Size (40-50 mm) and Cooling Air Velocity (2.5 m/s). Under this optimum condition, the predicted shelf life of the stored Sapota and the experimental results gave close values of less than 1.03 %. The number of days of shelf life extended for Sapota is 28days. Physio-chemical properties and microbial quality of stored Sapota was also evaluated. Percentage Loss in Weight was found to be maximum for control sample (13 %) whereas minimum for the cooled sample (0.04-0.123%). TSSincreased about 5%-7% for controlbut whereas for cooled sapota it was not more than 1-2%.

Numerical Investigation of a Radially Cooled Turbine Guide Vane Using Air and Steam as a Cooling Medium

Gas turbine performance is closely linked to the turbine inlet temperature, which is limited by the turbine guide vanes ability to withstand the massive thermal loads. Thus, steam cooling has been introduced as an advanced cooling technology to improve the efficiency of modern high-temperature gas turbines. This study compares the cooling performance of compressed air and steam in the renowned radially cooled NASA C3X turbine guide vane, using a numerical model. The conjugate heat transfer (CHT) model is based on the RANS-method, where the shear stress transport (SST) k−ω model is selected to predict the effects of turbulence. The numerical model is validated against experimental pressure and temperature distributions at the external surface of the vane. The results are in good agreement with the experimental data, with an average error of 1.39% and 3.78%, respectively. By comparing the two coolants, steam is confirmed as the superior cooling medium. The disparity between the coolants increases along the axial direction of the vane, and the total volume average temperature difference is 30 K. Further investigations are recommended to deal with the local hot-spots located near the leading- and trailing edge of the vane.

Simulation and Experimental Research on the Cooling Medium of Diamond Single Particles and Beads Cutting Reinforced Concrete

Diamond wire saw is the first choice for the demolition of reinforced concrete walls and is expected to work from top to bottom for a couple of weeks. However, the service life of the machine is greatly affected by dry operating conditions. What’s more, the thick and high walls make the effective cooling of working diamond wire saws even harder. To tackle the cooling problem in the work, not only was the cutting heat generated during the cutting process calculated to provide a theoretical basis for the simulation and experiments, but the FEM software AdvantEdge was used to simulate the cutting process. By applying four different cooling media and comparing the temperature change of the cutting zone as well as the force of the diamond particles, the best cooling scheme was obtained. What’s more, the effectiveness of the cooling medium in the simulation process was experimentally verified. In the end, microscopic wear of the diamond particles was observed by Scanning Electron Microscope to study the impact of different cooling media. The proposed cooling scheme is of major significance for the dismantling of decommissioned nuclear facilities with diamond wire saws.

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