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The recent progress of electronic control systems in vehicles is remarkable as evidenced by the development of electronic fuel injection systems,(EFI), automatic transmission control systems, and anti-lock brake systems,(ABS). The number of actuators for the systems has been increasing. Consequently, a need has been identified for a reduction in volume and number of the system actuators for control purposes. A composite magnetic material has been developed with the aim of miniaturizing magnetic solenoid valves for actuator applications. A composite magnetic material is such that both ferromagnetic and paramagnetic sections coexist within a single material, and can contribute to optimization of the magnetic circuit of a solenoid valve. This paper describes the development of a composite magnetic material, and its resultant characteristics.

A highly corrosion resistant drawn cup type evaporator was developed. During the development of this evaporator, the corrosion characteristics of evaporators in the field were examined in detail. Profound understanding of the corrosion mechanism led to the development of a new, unique, corrosion test method which simulates the actual evaporator field service environment. The main factors involved in increasing the corrosion resistance of the brazing sheet are (1) reduction of iron and silicon content in the core alloy and, (2) addition of titanium to the core alloy. In the present alloy, titanium content varies lamellarly through the thickness of the core alloy. Regions of high titanium content have a more cathodic potential, thus causing corrosion to proceed along the low titanium content lamellae. Consequently, the reduced iron and silicon contents, and the titanium addition, have the net effect of reducing the pitting corrosion rate.

Extensive work was conducted to develop a corrosion resistant brazing sheet alloy and to apply it to a drawn cup type evaporator in automotive air conditioning system. The items to be investigated included the influence of chemical composition of the core alloy on corrosion resistance, suppression of erosion during the brazing cycle, and enhancement of the brazing sheet formability. Additional investigation was conducted to develop a new corrosion test method on the basis of better understanding of the mechanism of corrosion in the field and to evaluate the corrosion resistance of a evaporator fabricated from the new alloy. This paper, as Part 1, describes the results of alloy development from the metallurgical and electrochemical point of view.