Cu-Zn-Al slurry catalysts were prepared using a complete liquid-phase preparation technology under different heat treatment atmospheres.The catalysts were characterized using X-ray diffraction,X-ray photoelectron spec...Cu-Zn-Al slurry catalysts were prepared using a complete liquid-phase preparation technology under different heat treatment atmospheres.The catalysts were characterized using X-ray diffraction,X-ray photoelectron spectroscope,and N2 adsorption-desorption.Their application in the single-step synthesis of dimethyl ether from syngas was also investigated.The results indicate that the type of heat treatment atmosphere has an influence on the Cu species and the Cu0/Cu＋ ratio on the catalyst surface.Moreover,the final Cu/Zn ratio on the catalyst surface is mainly dependent on the composition and reaction environment of the catalyst and less on the type of heat treatment atmosphere.The prepared catalysts can suppress sintering of active sites at high temperatures,and the type of heat treatment atmosphere mainly affects the capability of the catalyst for methanol synthesis.The catalysts perform best using N2 as the heat treatment atmosphere.展开更多
The considerable heat treatment induced runout value in the end face of the automobile main reducer gear is always dimensionally out of tolerance.It directly affects the dimensional accuracy,the grade of carburized an...The considerable heat treatment induced runout value in the end face of the automobile main reducer gear is always dimensionally out of tolerance.It directly affects the dimensional accuracy,the grade of carburized and hardened gears,and the post-quenching manufacturing costs.In this study,three dimensional numerical models were developed to simulate the carburizing-quenching process of gear based on the multi-field coupling theory using DEFORM software.The results indicated that the ununiform cooling rate of the gear caused by the asymmetry of the web structure would result in the ununiform distribution of martensite,leading to the large runout value at the end face of the gear.Therefore,a novel method was proposed to minimize the heat treatment induced runout value.It was found that the heat treatment induced runout value could be effectively controlled by the addition of a compensation ring and the support of a rod structure.Further experiments showed that the average runout value of the gear end face before and after the proposed heat treatment method were about 0.023 mm and 0.059 mm respectively,which was in good agreement with the simulated results.The novel approach proposed in this study led to a reduction of the gear runout value by 70.0%‒76.9%compared to that of the original heat treatment process,which may serve as a practical and economical way to predict and minimize the heat treatment induced distortion in drive gear.展开更多
Free quenching of automotive leaf springs is a new technology that has gradually started to be applied in the industry in China in recent years.Only a few manufacturers are applying it in the industry.Through more tha...Free quenching of automotive leaf springs is a new technology that has gradually started to be applied in the industry in China in recent years.Only a few manufacturers are applying it in the industry.Through more than half a year of on-site practice,the changes in the hot forming of spring plates before free quenching have been explored,and finally a heat treatment process that meets the production requirements of our company has been developed,achieving normal production.展开更多
IN the past five years the process combination of vacuum hardening, respectively vacuum carburizing with high-pressure gas quenching was successfully introduced to the market, especially in the manufacture of gears. I...IN the past five years the process combination of vacuum hardening, respectively vacuum carburizing with high-pressure gas quenching was successfully introduced to the market, especially in the manufacture of gears. In the meantime furnace concepts for various applications are available to the industry. In the following report three plant varieties are introduced, which differ in process flexibility and throughput. This report also explains criteria for the selection of a furnace in view of the existing application requirements. Besides this a short introduction is given into the vacuum carburizing process and the high-pressure gas quenching technology.展开更多
Numerical simulations based on a conjugate heat transfer solver have been carried out to analyze various gas quenching configurations involving a helical gear streamed by an air flow at atmospheric pressure in a gas q...Numerical simulations based on a conjugate heat transfer solver have been carried out to analyze various gas quenching configurations involving a helical gear streamed by an air flow at atmospheric pressure in a gas quenching chamber. In order to optimize the heat transfer coefficient distribution at key positions on the specimen, configurations involving layers of gears and flow ducts comprising single to multiple gears have been simulated and compared to standard batch configurations in gas quenching. Measurements have been performed covering the local heat transfer for single gears and batch of gears. The homogeneity of the heat transfer coefficient is improved when setting up a minimal distance between the gears (batch density) and when introducing flow ducts increasing the blocking grade around the gears. An offset between layers of the batch as well as flow channels around the gears plays a significant role in increasing the intensity and the homogeneity of the heat transfer in gas quenching process.展开更多
To shorten the process of face gears,the grinding-hardening effect experiment of face gears under minimum quantity lubrication(MQL)was carried out.Firstly,the grinding method of face gears was analyzed based on the en...To shorten the process of face gears,the grinding-hardening effect experiment of face gears under minimum quantity lubrication(MQL)was carried out.Firstly,the grinding method of face gears was analyzed based on the envelope principle,and the control equation of grinding movement was constructed.Secondly,the distribution ratio equation of heat flux density was established,and the theoretical calculation formula of triangle heat source was derived.Thirdly,since a MATLAB calculation program was compiled,the temperature change law under MQL grinding was analyzed.In the end,the influence of grinding parameters on the grinding-hardening layer depth was analyzed.The results demonstrate that MQL grinding achieves the grinding-hardening effect.展开更多
Induction heating has been widely used by the heat treatment industry mainly in the wind-power and automotive sectors,in particular for hardening purposes,in a broad range of applications,its main advantages being the...Induction heating has been widely used by the heat treatment industry mainly in the wind-power and automotive sectors,in particular for hardening purposes,in a broad range of applications,its main advantages being the high repeatability and easy automation of the process,both factors leading to improved manufacturing efficiency and reduced CO;emissions.Though,traditional furnace-based case hardening treatments still represent the choice of reference when performance requirements are particularly demanding,either for the critical operating conditions or safety-related issues.The processes of CIH（Contour Induction Hardening）,compared to the traditional carburizing processes,allows to reduce the deformations after heat treatment.The main purpose of these treatments,as well as increases the surface hardness of the piece,is to induce compressive stresses in the superficial layer,improving the fatigue behavior.A multiphysics magneto-thermal simulation can be developed in order to calculate the temperature distribution in the gear,setting the input parameters such as currents,frequencies and treatment times.展开更多
基金supported by the National Natural Science Foundation of China(No.20706039)the National Basic Research Program(973 Program) of China (No.2005CB221204)+1 种基金the Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi of China in 2010the Young Scientific and the Technical Fund of Shanxi of China (No.2006021010)
文摘Cu-Zn-Al slurry catalysts were prepared using a complete liquid-phase preparation technology under different heat treatment atmospheres.The catalysts were characterized using X-ray diffraction,X-ray photoelectron spectroscope,and N2 adsorption-desorption.Their application in the single-step synthesis of dimethyl ether from syngas was also investigated.The results indicate that the type of heat treatment atmosphere has an influence on the Cu species and the Cu0/Cu＋ ratio on the catalyst surface.Moreover,the final Cu/Zn ratio on the catalyst surface is mainly dependent on the composition and reaction environment of the catalyst and less on the type of heat treatment atmosphere.The prepared catalysts can suppress sintering of active sites at high temperatures,and the type of heat treatment atmosphere mainly affects the capability of the catalyst for methanol synthesis.The catalysts perform best using N2 as the heat treatment atmosphere.
基金National Key R&D Program of China(Grant No.2019YFB2004700)State Key Laboratory of High Performance Complex Manufacturing of China(Grant No.ZZYJKT2019-08)China Postdoctoral International Exchange Program(Grant No.140050004).
文摘The considerable heat treatment induced runout value in the end face of the automobile main reducer gear is always dimensionally out of tolerance.It directly affects the dimensional accuracy,the grade of carburized and hardened gears,and the post-quenching manufacturing costs.In this study,three dimensional numerical models were developed to simulate the carburizing-quenching process of gear based on the multi-field coupling theory using DEFORM software.The results indicated that the ununiform cooling rate of the gear caused by the asymmetry of the web structure would result in the ununiform distribution of martensite,leading to the large runout value at the end face of the gear.Therefore,a novel method was proposed to minimize the heat treatment induced runout value.It was found that the heat treatment induced runout value could be effectively controlled by the addition of a compensation ring and the support of a rod structure.Further experiments showed that the average runout value of the gear end face before and after the proposed heat treatment method were about 0.023 mm and 0.059 mm respectively,which was in good agreement with the simulated results.The novel approach proposed in this study led to a reduction of the gear runout value by 70.0%‒76.9%compared to that of the original heat treatment process,which may serve as a practical and economical way to predict and minimize the heat treatment induced distortion in drive gear.
文摘Free quenching of automotive leaf springs is a new technology that has gradually started to be applied in the industry in China in recent years.Only a few manufacturers are applying it in the industry.Through more than half a year of on-site practice,the changes in the hot forming of spring plates before free quenching have been explored,and finally a heat treatment process that meets the production requirements of our company has been developed,achieving normal production.
文摘IN the past five years the process combination of vacuum hardening, respectively vacuum carburizing with high-pressure gas quenching was successfully introduced to the market, especially in the manufacture of gears. In the meantime furnace concepts for various applications are available to the industry. In the following report three plant varieties are introduced, which differ in process flexibility and throughput. This report also explains criteria for the selection of a furnace in view of the existing application requirements. Besides this a short introduction is given into the vacuum carburizing process and the high-pressure gas quenching technology.
文摘Numerical simulations based on a conjugate heat transfer solver have been carried out to analyze various gas quenching configurations involving a helical gear streamed by an air flow at atmospheric pressure in a gas quenching chamber. In order to optimize the heat transfer coefficient distribution at key positions on the specimen, configurations involving layers of gears and flow ducts comprising single to multiple gears have been simulated and compared to standard batch configurations in gas quenching. Measurements have been performed covering the local heat transfer for single gears and batch of gears. The homogeneity of the heat transfer coefficient is improved when setting up a minimal distance between the gears (batch density) and when introducing flow ducts increasing the blocking grade around the gears. An offset between layers of the batch as well as flow channels around the gears plays a significant role in increasing the intensity and the homogeneity of the heat transfer in gas quenching process.
基金Supported by the Innovative Research Project of Basic Products of State Administration of Science,Technology and Industry for National Defense(237099000000170006)。
文摘To shorten the process of face gears,the grinding-hardening effect experiment of face gears under minimum quantity lubrication(MQL)was carried out.Firstly,the grinding method of face gears was analyzed based on the envelope principle,and the control equation of grinding movement was constructed.Secondly,the distribution ratio equation of heat flux density was established,and the theoretical calculation formula of triangle heat source was derived.Thirdly,since a MATLAB calculation program was compiled,the temperature change law under MQL grinding was analyzed.In the end,the influence of grinding parameters on the grinding-hardening layer depth was analyzed.The results demonstrate that MQL grinding achieves the grinding-hardening effect.
文摘Induction heating has been widely used by the heat treatment industry mainly in the wind-power and automotive sectors,in particular for hardening purposes,in a broad range of applications,its main advantages being the high repeatability and easy automation of the process,both factors leading to improved manufacturing efficiency and reduced CO;emissions.Though,traditional furnace-based case hardening treatments still represent the choice of reference when performance requirements are particularly demanding,either for the critical operating conditions or safety-related issues.The processes of CIH（Contour Induction Hardening）,compared to the traditional carburizing processes,allows to reduce the deformations after heat treatment.The main purpose of these treatments,as well as increases the surface hardness of the piece,is to induce compressive stresses in the superficial layer,improving the fatigue behavior.A multiphysics magneto-thermal simulation can be developed in order to calculate the temperature distribution in the gear,setting the input parameters such as currents,frequencies and treatment times.
