Sodium has been used for many years to modify aluminium silicon alloys. However, one problem associated with its use is that the sodium content declines or fades relatively quickly. As a result, controlling the sodium content within the defined limits, which is necessary for good casting properties can be difficult. Currently spectrometers or thermo analysis are used to monitor the sodium content, however, there is usually some delay between sampling and the test result, and the whole process can be time consuming and costly. An electrochemical sodium sensor has now been developed which is capable of giving an immediate and real-time read out of sodium content in exactly the same way that thermocouples are commonly used to monitor metal temperatures. This gives the foundryman the possibility to control the sodium levels within much tighter specifications and thus giving a much better control of the properties of the finished casting.
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