Key Engineering Materials Vol. 567

Abstract: In the thermomagnetism analysis, the ferromagnetic amorphous alloy near or after the Curie temperature within a certain scope was in the paramagnetic condition with low magnetization. When the heating temperature achieved the crystallization temperature of the amorphous alloy, the magnetization increased significantly due to the crystallization of the alloy. As the obvious crystallization of the amorphous alloy, the crystallization phase with a high Curie temperature (Tc) formed and the ferromagnetism of the alloy would not be fully transferred to paramagnetism. The magnetization of the alloy would maintain at a stable high level before it had been fully crystallized. Therefore, the structure of the ferromagnetic amorphous alloy can be identified accurately by the obvious difference between the thermomagnetism curves before and after crystallization.

Abstract: This study, by means of GC-MS and HPLC, investigated the characteristics of volatile organic compounds (VOCs) released from fiber hot-pressing in a medium density fiberboard (MDF) production line with a production capacity of 80,000 m3/a. The quantity of total volatile organic compounds (TVOC), aldehydes and ketones were calculated. The results showed that the concentration of TVOC reached 1.8940 mg/m3. The main components include terpenes, acrolein and acetone, benzenes series and saturated hydrocarbons. The concentration of the mixture of aldehydes and ketones was 5.1136 mg/m3.

Abstract: Aiming at the key techniques in ECM, the ECM system has been developed. The micro-tool-electrode and workpiece have been machined on the machine tool. Base on the experiment analysis of the effect of voltage, immersion depth, power characteristics on its forming laws in the micro-tool-electrode machining, the ECM has been realized in low concentration alkaline electrolyte. A micro-tool-electrode with the length of 1200 um, the diameter of 16 um, and aspect ratio of 75:1 has been machined by the developed machine tool.

Abstract: Electrochemical micro-machining (EMM) has become one of the main machining methods for production of miniaturized parts and components. Utilizing the developed EMM set-up, the effects of ultrasonic wave frequency on characteristics of localized dissolution and accuracy of micro-hole in EMM are investigated and evaluated. The experiment results demonstrate that the accuracy of micro-hole and characteristics of localized dissolution can become better with the increase of ultrasonic wave frequency. The accuracy of micro-hole machined by 26KHZ can improve about 30% than that by 16KHZ. Moreover, the ability of localized dissolution by 26KHZ can be increased about 27%-30%.

Abstract: The machining of PMMCs is very difficult due to the highly abrasive and intermittent nature of the reinforcement. It is therefore necessary to choose tool material wisely. The focus of this paper was to assess performance of CBN-uncoated, CBN-coated and PCD tools with respect to tool wear, wear mechanism and cutting force while turning of Al 2124 SiC (45%wt) Particulate Metal Matrix Composite. Experimental results reveal that abrasion and chipping presented the most prevalent mode of wear among the CBN-uncoated, CBN-coated and PCD tools. Flank and crater wear were observed in all tools with flank wear being more prevalent in CBN-coated and CBN-uncoated tools. Wear among PCD tool was low as compared to CBN-uncoated CBN-coated. PCD tool is more suitable for cutting Al 2124 SiC(45%wt) PMMC.

Abstract: Ultrasonic vibration assisted turning has significant improvements in processing of intractable materials compared to conventional turning. This paper presents a theoretical investigation of tool wear in single point diamond turning of ferrous metals based on numerical simulation. Finite element modeling and simulation of ultrasonic vibration turning process were performed, aimed at optimizing a series of technological parameters in the process of machining, reducing tool wear and improving surface quality as much as possible. The results revealed that the cutting speed and depth of cut are two crucial factors for tool wear, unlike the other parameters of vibration frequency, amplitude and flank angle. Moreover, this technological measure has observably decreased the cutting force and cutting temperature, so as to obtain superior surface finish.

Abstract: The high speed jet-electrodepositing equipment was used to prepare Ni-P alloy in substrate of 45 steel. The influences of current density on depositing rate, hardness of deposit and microstructure of Ni-P alloy were studied, and the comparation with that of conventional electroplating were studied. The results show that with the increase of stirring intensity of the electrolyte, the thickness of diffused layer decreases, the critical current density increases, and then the depositing rates increase to 69.82/min. A linear increasing of the depositing rate with the increase of current density is observed, and it refines grain size obviously. Deposit hardness up to 679HV.

Abstract: CRFHCP RF hollow cathode plasma graft polymerization has characteristics of discharge density, high discharging efficiency, good surface modification effect, discharge area and regional separation, applies to modify large area thin film material surface. The uniformity modifying large area plasma material surface is the technical difficulty related technical personnel has been concerned with, the key point restricting HCRFCP technology industrialization application too. This paper analyzes influence factors of the large area thin film materials plasma graft polymerization uniformity; applies simulation software and mathematical models; makes optimized design to the hollow cathode discharge electrodes and graft polymerization distributing pipe. The experiment proved, the uniformity processing large area battery diaphragm is better to apply the hollow cathode plasma graft polymerization, and is suitable for industrial application.

Abstract: The large hydrogenated cylindrical shell is an important part of petrochemical pressure vessels. From the macroscopic aspects, the influence that the surface defects of the large hydrogenated cylindrical shells forging blank has on the high efficiency machining was analyzed in the paper firstly. Then, through the chemical point of view, the new chemical components of the shells material were known, and the shells material physical properties were also dissected. The phenomenon of compatibility between the Co element which is in tools material and the siderophile element of the 2.25Cr-1Mo-0.25V steel which is the material of the large hydrogenated cylindrical shell was found. Therefore, the technical performance requirements of the heavy-duty turning tool which is to achieve the goal of high efficiency cutting were put forward. Through researching the chemical and the physical properties of the shell, the new high-efficiency turning tool was designed from the aspects of the tools material and the tools geometric structure. Finally, the comparative test between the new heavy-duty turning tool which was named XF8 and the YT5 tool which was being used in factory was made, and by way of comparing both the service life and the chip-breaking performance of XF8 with YT5s, the test results showed that the XF8 met the requirements of high-efficiency heavy-duty turning, and the feasibility of the tools design scheme was further verified.