Study On The Preparation Of Type K Thin-film Thermocouple By PVD

Thermocouples are temperature sensors which are being widely used in industry,scientific research.Its advantages are wide temperature range,rugged,no self-heating phenomenon,ease of use.In addition to the advantages mentioned above,thin-film thermocouple also have smaller heat capacity,fast response,smaller outline,and little effect on the measured object.We select magnetron sputtering,E-beam evaporation and arc ion plating to prepare the K type thin-film thermocouple.One part of the samples' NiCr/NiSi films are both deposited by magnetron sputtering and another part of the samples' NiCr film is deposited by magnetron sputtering,the samples' NiSi film is deposited by E-beam deposition.The thin film is calibrated and characterized by SEM(EDS),Digital Temperature Monitor and temperature controlled oven.The result prove that the element constitution of all the samples is differ from the target and the average Seebeck coefficient is differ from National Standard either.After analysis we consider the main reasons as below:(1)During magnetron sputtering,the sputtering rate and the threshold energy value is the key reason which cause the segregation between film and target.The more the sputtering rate and the threshold energy varied,the more the segregation varied.This variation is also affected by the experiment sequence,which means as the experiment goes on,the segregation between film and target will decrease.This is because the atom density is different between the target surface and inner target,thus the atom will diffuse from deeper layer to the surface.(2)In the e-beam evaporation,the segregation between NiSi target and NiSi film is mainly caused by the difference in density between molten Ni and Si.This variation is also affected by the experiment sequence,which means as the experiment goes on,the segregation between film and molten material will increase.This is because the molten Si float on Ni throughout the experiment,thus the molten Si is evaporated out and only Ni is remained at last.In addition,we study the problem of deposition magnetic material on ion arc plating equipment and simulate by FEM.Analyze the difference in ferro-magnetic material and non-ferro-magnetic material when being discharged in ion arc plating and reason why the arc escape from the target surface.At the end of the research we propose some approach to solve the arc from escaping.