Development Of A Device For Measuring Hydrogen Content In Molten Aluminum Alloy With Inert Gas Circulation Method

With the increasingly widespread application of the aluminum alloy,metallargist and foundrymen are increasingly concerned about the quality of aluminum alloy castings.Hydrogen in the aluminum alloy melt is one of the main factors to affect the quality in aluminum alloy castings,therefore it is important for controlling the quality of aluminum alloy castings to detect accurately and quantitatively hydrogen content of aluminum alloy melt.In this paper,we developed a rapid and quantitative detection device of hydrogen content in the aluminum alloy melt that is based on inert gas circulation method and computer measurement and control technology.The device includes two parts of inert gas circulation system and computer computer measurement and control unit.The inert gas circulation system that can implement the function of flushing,the hydrogen content detection and calibration under the control of computer monitoring and control unit is mainly composed of vacuum regulator valve,flow regulating valve,solenoid valves,micro diaphragm pump,thermal conductivity detector,flowmeter,probe,temperature measuring device,etc.In order to reduce testing costs and shorten the detection time,the probe is divided into two parts of the probe body and the porous graphite rod,through the threaded connection between the porous graphite rods and probe body.The temperature measuring device use a K-type thennocouple which structure is sheathed structure as the temperature sensor.Hardware system of computer computer measurement and control unit adopts modularized design scheme,the analog input module ADAM-4118 as the analog input channel to detect hydrogen partial pressure signal and temperature signal,the digital input/output module ADAM-4050 as switch output channel to control the solenoid valve,micro switch pump and thermal conductivity detector of the inert gas circulation system.Interface converter for ADAM-4520,is the role of RS-232 serial port into RS-485 serial port,so that the computer can also connect analog input channel and digital output channel.Modular design can improve the system integration and dramatically shorten the development cycle.Software system of the computer measurement and control unit using Microsoft Visual Basic 6.0 write,can realize hydrogen content detection function,calibration function,history view function,alloy parameter add function and test report generation function and manual control functions.The optimal working parameters were determined through the commissioning of the appliance.The device was calibrated for four point three segment by pure argon,argon containing 1%hydrogen,pure nitrogen and pure helium.Different components of aluminum alloy melt were tested using the device.Tests show that the unit operation is simple,quickly and accurately quantitative,and meet the development requirements,can be used in practical production.