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Steels for plastic injection moulds are available in different alloy compositions. Mechanical properties, such as wear resistance and hardness, are the most important properties of these steels. Corrosion resistance of these steels is also an important property, which is why there are high-alloy steel compositions.
The cooling and temperature control systems for moulds have different types of fluid circuits. There are open and closed systems, which has a direct influence on the oxygen content in the fluid. There are also different types of water, such as hard and soft water, and different types of additives, for example biocides or corrosion inhibitors.
The aim of this work is to investigate the corrosion behaviour of various typical plastic mould steels under high and low oxygen conditions. With these results, a mould tempering device will be developed that controls the oxygen content in a closed water-based liquid system. If this is successful, chemical additives can be dispensed with and good corrosion behaviour can be achieved, even for low and unalloyed steels.
Steels with different chromium contents typical for this application were selected for the tests. Heat treatment was carried out in a typical way for these steels. Corrosion behaviour was measured by open circuit and potentiodynamic measurements in soft water at 50°C. Oxygen-free and oxygen-saturated conditions were investigated.
Carbon fiber-epoxy laminates are used in aerospace manufacturing, e.g. as substrates for solar cells of satellites. Commonly, fibers or fibermats are impregnated with epoxy resin and placed in the required orientation. During subsequent curing, the resin molecules are crosslinked. Cured parts are characterized by their glass transition temperature (Tg). It has been observed that Tg of epoxy matrix resin vary with recorded absolute air humidity during wet fiber placement manufacturing. Based on the production data of a series production of 203 carbon fiber laminates for space application, an empirical linear relationship between the absolute air humidity at the beginning of each production day and the observed glass transition temperature of the fully cured laminate is formulated and validated. The empirical equation describes a linear decrease of achievable glass transition temperature with increasing absolute air humidity. The quantitative nature of the results encourages straightforward practical application to determine the maximum achievable Tg for given production conditions.
