The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting indust...The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting industry.To apply the GISS process with a die casting process,a GISS maker unit is designed and attached to a conventional die casting machine with little modifications.The commercial parts are developed and produced by the GISS die casting process.The GISS die casting shows the feasibility to produce industrial parts with aluminum 7075 and A356 with lower porosity than liquid die casting.展开更多
Several rheocasting processes are developed or applied worldwide in the metal forming industry.One of the new rheocasting processes is the gas induced semi-solid(GISS) process.The GISS process utilizes the principle o...Several rheocasting processes are developed or applied worldwide in the metal forming industry.One of the new rheocasting processes is the gas induced semi-solid(GISS) process.The GISS process utilizes the principle of rapid heat extraction and vigorous local extraction using the injection of fine gas bubbles through a graphite diffuser.Several forming processes such as die casting,squeeze casting,gravity casting,and rheo-extrusion of the semi-solid slurries prepared by the GISS process have also been conducted.The GISS process is capable of processing various alloys including cast aluminum alloys,die casting aluminum alloys,wrought aluminum alloys,and zinc alloys.The GISS process is currently developed to be used commercially in the industry with the focus on forming semi-solid slurries containing low fractions solid(< 0.25) into parts.The research and development activities of the GISS process were discussed and the status of the industrial developments of this process was reported.展开更多
The feasibility of semi-solid die casting of ADC12 aluminum alloy was studied. The effects of plunger speed, gate thickness, and solid fraction of the slurry on the defects were determined. The defects investigated ar...The feasibility of semi-solid die casting of ADC12 aluminum alloy was studied. The effects of plunger speed, gate thickness, and solid fraction of the slurry on the defects were determined. The defects investigated are gas and shrinkage porosity. In the experiments, semi-solid slurry was prepared by the gas-induced semi-solid （GISS） technique. Then, the slurry was transferred to the shot sleeve and injected into the die. The die and shot sleeve temperatures were kept at 180 ℃ and 250 ℃, respectively. The results show that the samples produced by the GISS die casting give little porosity, no blister and uniform microstructure. From all the results, it can be concluded that the GISS process is feasible to apply in the ADC12 aluminum die casting process. In addition, the GISS process can give improved properties such as decreased porosity and increased microstructure uniformity.展开更多
The semi-solid metal forming using high pressures has been applied for several years.In contrast,low pressure casting,such as gravity sand casting,has not been widely studied even though it may help reduce porosity de...The semi-solid metal forming using high pressures has been applied for several years.In contrast,low pressure casting,such as gravity sand casting,has not been widely studied even though it may help reduce porosity defects and offer a better casting yield.A semi-solid gravity sand casting process using the Gas Induced Semi-Solid process was investigated.The results show that the process can produce complete parts with no observable defects.The ultimate tensile strength and elongation data of semi-solid cast samples are higher than those of the liquid cast samples.In addition,the semi-solid sand casting process gives a better casting yield.It can be concluded that the semi-solid sand casting of an aluminum alloy using the GISS process is a feasible process.展开更多
The gas induced semi-solid(GISS) process was developed to create semi-solid slurry with fine and uniform globular structure.The combination of local rapid heat extraction and vigorous agitation by the injection of fin...The gas induced semi-solid(GISS) process was developed to create semi-solid slurry with fine and uniform globular structure.The combination of local rapid heat extraction and vigorous agitation by the injection of fine inert gas bubbles through a graphite diffuser in molten metal held at a temperature above its liquidus temperature changes the morphology of primary α(Al) from coarse dendritic to rosette-like and finally to fine globular.The GISS process produced semi-solid slurry at low solid fractions and then formed the slurry by a squeeze casting process to produce casting parts.The effects of primary phase morphology on the mechanical properties of Al-Si-Mg-Fe alloy were investigated.The results show that the ultimate tensile strength and elongation are affected by the shape factor and particle size of the primary α(Al).展开更多
An aluminum extrusion process is mainly used to fabricate long tubes, beams and rods for various applications. However, this process has a high production cost due to the need for investment of high-pressure machinery...An aluminum extrusion process is mainly used to fabricate long tubes, beams and rods for various applications. However, this process has a high production cost due to the need for investment of high-pressure machinery. The objective of this work is to develop a new semi-solid extrusion process using semi-solid slurry at low solid fractions. A laboratory extrusion system was used to fabricate aluminum rods with the diameter of 12 ram. The semi-solid metal process used in this study was the gas induced semi-solid （GISS） technique. To study the feasibility of the GISS extrusion process, the effects of extrusion parameters such as plunger speed and solid fi-action on the extrudability, microstructure, and mechanical properties of extruded samples were investigated. The results show that the plunger speed and solid fraction of the semi-solid metal need to be carefully controlled to produce complete extruded parts.展开更多
The anodizing parameters of voltage, current density, temperature, and electrolyte choice were assessed to find an appropriate combination for the superheated slurry cast 7075 Al alloy substrate.The alloy was anodized...The anodizing parameters of voltage, current density, temperature, and electrolyte choice were assessed to find an appropriate combination for the superheated slurry cast 7075 Al alloy substrate.The alloy was anodized in sulfuric acid electrolyte or alternatively in sulfuric acid mixed with boric acid or citric acid. The voltages applied were in the range of 15-30 V. Anodizing current densities tested were 2 and 3 A/dm^2,while temperatures tested were 5 and 15 ℃. Thickness, surface morphology, hardness,and corrosion resistance of the oxide film were then evaluated.It was found that 25 V,2 A/dm^2 and 5 ℃ were suitable for this alloy when anodized in sulfuric acid. The oxide film was smooth with uniform thickness, low porosity, high hardness,and had the highest corrosion resistance at these parameters. However, discontinuous oxide films were observed from samples anodized at higher temperature of 15 ℃.Alternative electrolytes considered were sulfuric acid mixed with boric acid or citric acid. The results showed that electrolytes with boric acid or citric acid increased thickness, hardness, corrosion resistance and quality of the oxide films.However, these oxide films were inferior to those obtained with sulfuric acid electrolyte at lower temperature(25 V, 2 A/dm^2 and5 ℃).展开更多
基金supports from Prince of Songkla University (No.AGR530031M)the Royal Golden Jubilee Ph.D program (No.PHD/0173/2550)
文摘The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting industry.To apply the GISS process with a die casting process,a GISS maker unit is designed and attached to a conventional die casting machine with little modifications.The commercial parts are developed and produced by the GISS die casting process.The GISS die casting shows the feasibility to produce industrial parts with aluminum 7075 and A356 with lower porosity than liquid die casting.
基金supports from several sources including the Thai Research Fund (No. MRG5280215)Prince of Songkla University (No. AGR530031M)the Royal Golden Jubilee Ph.D. Program (No. PHD/0134/2551 and PHD/0173/2550)
文摘Several rheocasting processes are developed or applied worldwide in the metal forming industry.One of the new rheocasting processes is the gas induced semi-solid(GISS) process.The GISS process utilizes the principle of rapid heat extraction and vigorous local extraction using the injection of fine gas bubbles through a graphite diffuser.Several forming processes such as die casting,squeeze casting,gravity casting,and rheo-extrusion of the semi-solid slurries prepared by the GISS process have also been conducted.The GISS process is capable of processing various alloys including cast aluminum alloys,die casting aluminum alloys,wrought aluminum alloys,and zinc alloys.The GISS process is currently developed to be used commercially in the industry with the focus on forming semi-solid slurries containing low fractions solid(< 0.25) into parts.The research and development activities of the GISS process were discussed and the status of the industrial developments of this process was reported.
基金funded by the Royal Golden Jubilee Ph.D. Program (Grant No.PHD/0173/2550)the Thai Research Fund (Contract number MRG5280215)Prince of Songkla University (Contract No.AGR530031M)
文摘The feasibility of semi-solid die casting of ADC12 aluminum alloy was studied. The effects of plunger speed, gate thickness, and solid fraction of the slurry on the defects were determined. The defects investigated are gas and shrinkage porosity. In the experiments, semi-solid slurry was prepared by the gas-induced semi-solid （GISS） technique. Then, the slurry was transferred to the shot sleeve and injected into the die. The die and shot sleeve temperatures were kept at 180 ℃ and 250 ℃, respectively. The results show that the samples produced by the GISS die casting give little porosity, no blister and uniform microstructure. From all the results, it can be concluded that the GISS process is feasible to apply in the ADC12 aluminum die casting process. In addition, the GISS process can give improved properties such as decreased porosity and increased microstructure uniformity.
基金the funding from Princeof Songkla University for Ph.D. 50% Scholarship,the Royal Golden Jubilee Ph.D. program (Grant No.PHD/0173/2550)
文摘The semi-solid metal forming using high pressures has been applied for several years.In contrast,low pressure casting,such as gravity sand casting,has not been widely studied even though it may help reduce porosity defects and offer a better casting yield.A semi-solid gravity sand casting process using the Gas Induced Semi-Solid process was investigated.The results show that the process can produce complete parts with no observable defects.The ultimate tensile strength and elongation data of semi-solid cast samples are higher than those of the liquid cast samples.In addition,the semi-solid sand casting process gives a better casting yield.It can be concluded that the semi-solid sand casting of an aluminum alloy using the GISS process is a feasible process.
文摘The gas induced semi-solid(GISS) process was developed to create semi-solid slurry with fine and uniform globular structure.The combination of local rapid heat extraction and vigorous agitation by the injection of fine inert gas bubbles through a graphite diffuser in molten metal held at a temperature above its liquidus temperature changes the morphology of primary α(Al) from coarse dendritic to rosette-like and finally to fine globular.The GISS process produced semi-solid slurry at low solid fractions and then formed the slurry by a squeeze casting process to produce casting parts.The effects of primary phase morphology on the mechanical properties of Al-Si-Mg-Fe alloy were investigated.The results show that the ultimate tensile strength and elongation are affected by the shape factor and particle size of the primary α(Al).
基金the financial supports from Prince of Songkla University (Contract number AGR530031M)
文摘An aluminum extrusion process is mainly used to fabricate long tubes, beams and rods for various applications. However, this process has a high production cost due to the need for investment of high-pressure machinery. The objective of this work is to develop a new semi-solid extrusion process using semi-solid slurry at low solid fractions. A laboratory extrusion system was used to fabricate aluminum rods with the diameter of 12 ram. The semi-solid metal process used in this study was the gas induced semi-solid （GISS） technique. To study the feasibility of the GISS extrusion process, the effects of extrusion parameters such as plunger speed and solid fi-action on the extrudability, microstructure, and mechanical properties of extruded samples were investigated. The results show that the plunger speed and solid fraction of the semi-solid metal need to be carefully controlled to produce complete extruded parts.
基金financially supported by the Higher Education Research Promotionthe National Research University Project of Thailand, Office of the Higher Education (Contract No. ENG580529S)+2 种基金Center of Excellence in Materials Engineering (CEME)the Graduate Engineer Scholarship and the Graduate School ScholarshipPrince of Songkla University, including Surat Thani Campus (2016)
文摘The anodizing parameters of voltage, current density, temperature, and electrolyte choice were assessed to find an appropriate combination for the superheated slurry cast 7075 Al alloy substrate.The alloy was anodized in sulfuric acid electrolyte or alternatively in sulfuric acid mixed with boric acid or citric acid. The voltages applied were in the range of 15-30 V. Anodizing current densities tested were 2 and 3 A/dm^2,while temperatures tested were 5 and 15 ℃. Thickness, surface morphology, hardness,and corrosion resistance of the oxide film were then evaluated.It was found that 25 V,2 A/dm^2 and 5 ℃ were suitable for this alloy when anodized in sulfuric acid. The oxide film was smooth with uniform thickness, low porosity, high hardness,and had the highest corrosion resistance at these parameters. However, discontinuous oxide films were observed from samples anodized at higher temperature of 15 ℃.Alternative electrolytes considered were sulfuric acid mixed with boric acid or citric acid. The results showed that electrolytes with boric acid or citric acid increased thickness, hardness, corrosion resistance and quality of the oxide films.However, these oxide films were inferior to those obtained with sulfuric acid electrolyte at lower temperature(25 V, 2 A/dm^2 and5 ℃).
