Application to construction and acceleration sensor of a Fe-Ni alloyed stress impedance element by electrodeposition method.

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Electrodeposited Fe-Ni alloys have been widely used for the thin film head of magnetic recording because of their high magnetic permeability and small coercive force. In recent years, the application of Fe-Ni alloy films to the stress sensor of magnetostriction type has been expected. This type of stress sensors detect the tension, torque, stress and weight loaded to the subject by using the reverse magnetostrictive effect that their magnetic property changes depending on the strain applied to magnetic substances. It has been well known that the deposition behavior of Fe-Ni alloys showed a typical feature of anomalous codeposition, in which electrochemically less noble Fe deposits preferentially under most plating conditions. Since the magnetic properties of Fe-Ni alloy change greatly depending on its composition, the alloy of fixed con position should be deposited stably to keep the desired properties. Therefore, it is important to make clear the mechanism of anomalous deposition of F … More e-Ni alloys.Deposition of Fe-Ni alloys was performed under various plating conditions in the sulfate solutions and the deposition behavior was compared with that of Zn-iron-group metal alloy, The results obtained are described as follows.The deposition behavior of Fe-Ni alloys showed a typical feature of the anomalous codeposition, in which electrochemically less noble Fe deposits preferentially under most plating conditions. This anomalous codeposition was caused by the suppression of Ni deposition due to the codeposition of Fe.The anomalous codeposition behavior in Fe-Ni alloy deposition was evidently dependent on the pH buffer capacity of the solutions. This can be explained in term of the preferential adsorption of FeOH on the deposition sites of more noble Ni due to the extremely smaller dissociation constant of FeOH+ than NiOH+ in the multi-step reduction process of hydrated iron-group metal ions.The degree of the preferential of less noble Fe was decreased under the plating conditions that the formation of FeOHad retarded.The magnetic coercive force of the deposited alloy films depends remarkably on their chemical composition as well as on their crystal grain size. Less