负压回升速率法铝合金熔体含气量检测装置

发布时间：2018-04-17 18:13

本文选题：氢分压 + 氢含量　；参考：《哈尔滨理工大学》2017年硕士论文

【摘要】：氢是唯一大量溶于铝熔体的有害气体,极易使铸件产生气孔、缩松等缺陷,从而降低其性能。目前,国内外炉前检测技术众多,大多检测方法不是需要等待氢扩散平衡这一过程,就是需要采用先进的高成本探头,从而大大增加其检测难度。因此研究一种快速、低成本的在线测氢装置,对铝合金测氢及除气具有十分重要的意义。本文从分析国内外多种测氢技术出发,总结了各种测氢技术及设备的特点,结合国内外测氢技术的优缺点,研究出了一种低成本、快速的测氢方法-负压回升速率测氢法。了解并分析了铝合金熔体中气体氢的来源,叙述了铝合金熔体中析氢动力学过程及氢在熔体中的溶解及扩散过程,详细介绍了铝合金熔体中氢气泡的形成及析出过程,通过对铝合金熔体中氢气泡的分析,以负压回升速率为原理,结合计算机采集及控制系统,研制出负压回升速率法测氢装置,并根据测氢功能的需要,将测氢系统分为标定系统及测试系统两个部分:标定系统主要包括配置不同氢含量铝合金熔体及实现建立铝合金熔体中氢分压与负压回升速率关系数据库的功能;测试系统主要以实现测量铝合金熔体中氢分压负压回升速率,并据此计算出熔体氢含量的功能。测氢系统主要由硬件和软件两个部分组成,硬件部分主要包括制造真空环境的真空泵、控制气路开关的电磁阀、控制电磁阀开关的继电器、实现数据采集和计算分析的计算机系统、实现温度和压力传感器所测得的信号转换模块、提供气体扩散环境的真空缓冲室及管路、连接测量装置与铝合金熔体的探头;软件部分程序采用Delphi语言编制,主要通过程序界面实现测氢系统中各电磁阀的开启与关闭,从而实现熔配、标定和测氢功能的转换,同时完成温度与压力传感器的数据采集与分析,实时以曲线和数据的形式同时显示在软件界面上,并最终显示测试结果。使用该装置进行了不同铝合金熔体含氢量的配置、不同铝合金熔体含氢量与负压回升速率对应关系的标定,并对不同含氢量铝合金熔体进行了测试。测试结果表明:该装置具有低成本、快速测量和测量准确的特点,经过今后的改进及优化可以满足在线实测要求。
[Abstract]:Hydrogen is the only harmful gas dissolved in aluminum melts, which can easily lead to defects such as porosity and shrinkage of castings, thus reducing its properties.At present, there are many technologies at home and abroad, most of the detection methods either need to wait for the process of hydrogen diffusion equilibrium, or need to use advanced high cost probe, which greatly increases the difficulty of detection.Therefore, it is very important to study a fast and low cost on-line hydrogen measuring device for aluminum alloy.Based on the analysis of various hydrogen measurement technologies at home and abroad, this paper summarizes the characteristics of various hydrogen measurement technologies and equipment. Combining the advantages and disadvantages of the domestic and foreign hydrogen measurement technologies, a low cost and fast hydrogen measurement method, the negative pressure pick-up rate hydrogen measurement method, is developed.The source of gas hydrogen in aluminum alloy melt is analyzed, the kinetics of hydrogen evolution in aluminum alloy melt, the process of hydrogen dissolution and diffusion in the melt are described, and the formation and precipitation process of hydrogen bubble in aluminum alloy melt are introduced in detail.Based on the analysis of hydrogen bubble in aluminum alloy melt and the principle of negative pressure pick-up rate, combined with the computer acquisition and control system, a hydrogen measuring device with negative pressure pick-up rate method was developed, and according to the requirement of hydrogen measurement function,The hydrogen measurement system is divided into two parts: the calibration system mainly includes the aluminum alloy melt with different hydrogen content and the function of establishing the relationship between hydrogen partial pressure and negative pressure recovery rate in aluminum alloy melt;The main purpose of the measurement system is to measure the hydrogen partial pressure recovery rate in aluminum alloy melt and calculate the function of hydrogen content in the melt.The hydrogen measurement system consists of two parts: hardware and software. The hardware mainly includes vacuum pump for manufacturing vacuum environment, solenoid valve for controlling gas path switch, relay for controlling solenoid valve switch.The computer system of data acquisition and calculation and analysis is realized, the signal conversion module measured by temperature and pressure sensor is realized, the vacuum buffer chamber and pipeline in gas diffusion environment are provided, and the measuring device is connected with the probe of aluminum alloy melt.The software part of the program is programmed by Delphi language, which realizes the opening and closing of the solenoid valves in the hydrogen measurement system through the program interface, so as to realize the conversion of the functions of fusion, calibration and hydrogen measurement.At the same time, the temperature and pressure sensor data acquisition and analysis are completed, and real-time display in the form of curves and data on the software interface, and finally display the test results.The configuration of hydrogen content in different aluminum alloy melts and the relationship between hydrogen content of different aluminum alloy melts and the recovery rate of negative pressure were calibrated with this device, and the different hydrogen content aluminum alloy melts were tested.The test results show that the device has the characteristics of low cost, rapid measurement and accurate measurement, which can meet the requirements of on-line measurement through future improvement and optimization.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG292

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