High pressure die casting (HPDC) is the dominant process for the production of magnesium components with complex configuration having typically thin to medium wall thickness. The growing use of die cast Mg alloys in the automotive industry, particularly for the production of drive-train components, has led to the development of creep resistant alloys, MRI153M and MRI230D, which were launched into the market several years ago. The present paper aims at exploring the effect of the HPDC process parameters on the porosity and, as a result, on the properties of the two MRI's developed alloys in comparison with common alloys AZ91D and AM50A that are usually considered as benchmark die casting alloys. The outcome of the research performed includes processing guidelines and recommendations, which allow obtaining high quality sound castings. These recommendations should be implemented in the course of design, optimization and production of highperformance components for various applications.
The flow behaviour of 4‐(Dimethylsilyl) butyl ferrocene‐grafted HTPB‐based composite propellant (P01) and basic aluminized HTPB‐based propellant (P02) was investigated using shear rheometer. The experimental data were fitted to ‘power law’ for non‐Newtonian fluid flow, and the rheological parameters were expressed as consistency index (k) and pseudoplasticity index (n). For both the propellant compositions, a shear thinning nature (pseudoplasticity index; n < 1) has been observed. The study categorically showed that the incorporation of 4‐(Dimethylsilyl) butyl ferrocene‐grafted HTPB has resulted in increased consistency index (k) and yield stress as compared to HTPB based compositions. In addition, the time–temperature cure‐kinetics study suggested that the rate of curing reaction is higher with toluene diisocyanate as compared to isophorone diisocyanate and the Arrhenius activation energy (Ea) corroborated with the observed trend. Furthermore, the Haegen–Poisseuille equation modified for non‐Newtonian fluid flow has been employed to determine the theoretical casting rate for 4‐(Dimethylsilyl) butyl ferrocene‐grafted HTPB‐based composite propellant at different temperatures in a vacuum casting setup.
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