Study On Optical Fiber Sensor Testing System For Alloy's Solidification Temperature Field

The temperature field of alloy's solidification process can in some sense reveal the essence of alloy's solidification. To predict alloy's structure and properties according to its solidification through testing its temperature field has caught much of attention. Using thermocouple is the most popular method, which has many disadvantages such as low resistance to oxidation and deoxidization, liability to be disturbed by electromagnetism, obvious thermal lag, etc. The instead method using optical fiber can solve has those problems. But none of existing fiber pyrometers which are designed for liquid metals can be used to test the temperature during transformation from liquid to solid, in other word, the solidification process. This article put forward a self-designed optical fiber temperature testing system right suitable for test of alloy's solidification temperature field.The theory of radiation temperature measurement is related, on the basis of which there are all-spectrum mode, single wavelength mode and colorimetric mode. Compare the three modes and then adopt colorimetry for it's insensitive to emissivity and environment. The temperature testing system designed in colorimetry consists of optical fiber detector, light transmitting route and electrical testing part.A new kind of consumptive optical fiber detector is designed which uses ceramic tubes made of Partially Stabilized Zirconia to protect the fiber in molten metal. Threads of optical fiber can be assembled to form an integrated detector according to the test require. Practice convinced that the detector is smart, cheap and operable.The light transmitting route output two rays in different wavelength as requisite of colorimetry. Profit from the technique of Wavelength Division Multiplex widely used in fiber-optic communications, the system realizes division and filter of radiate light by one component called demultiplexer. Thus it is smaller in form and more stable in performance then old structure consists of prisms and intervenient filters.The function of electrical testing part is convert signal from photic to electrical and then collect it and storage data. BPW77 photo-dynatron and AD620 meter amplifier are adopted in convert and amplify circuit. The ADuC812 SCM, produced by the Analog Device Corporation, in which integrated a 12 bits A/D converter is...