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Research

Near-net-shape process results in castings of high integrity, completeness, dimensional accuracy and minimal finishing. CNPM has collaborative partnerships with industry, particularly with automotive and aerospace sectors. The research envisages alloy development, solidification processing, optimization of manufacturing processes and innovative technologies for vehicles of the future. The research team is actively engaged in aluminum and magnesium alloys with a record of accomplishment in increased thermal and mechanical efficiency, weight reduction and reduced fuel consumption and emissions.

Novel methodologies, modeling techniques and phenomenological investigations with unique contributions to predicting hot tearing and improving castability of magnesium alloys were developed. Breakthrough research in understanding the factors (shrinkage, intermetallics, alloying elements, thermo-fluid effects and the related stress-strain development) in permanent mould casting of magnesium alloys. Pioneering analysis of hot tearing in permanent mould casting of magnesium and aluminum alloys using neutron diffraction resulted in determining triggering levels of residual internal stresses. Citation within 2008 Top 10 AFS Trans. Papers of Innovation and Impact (Bichler, AFS Trans 2008), AFS Magnesium Division Outstanding Organization Award 2010. Neutron diffraction was also used to analyze the effect of grain refinement on the hot tearing susceptibility (D’Elia, Advanced Materials Research, 2012) as well as on the eutectic modification of aluminum alloys (Vandersluis, Journal of Alloys and Compounds, 2017).

In-depth characterization of engine block and cylinder head microstructure, mechanical and thermal properties, and residual stress from each processing stage (as-cast, heat treated and service tested) enabled a scientific explanation for development of distortion (Lombardi, SAE Int. J. Mater. Manuf., 2013; Vandersluis, Materials Science and Engineering A, 2015). This directly improved fuel efficiency, reduced fuel consumption, reduced fuel leakage and reduced exhaust fumes. 2010 AUTO21-APMA Annual Conference poster competition: First prize in Theme C (Materials and Manufacturing); within Top Five Prize for all themes across Canada. Technology transfer to General Motors/Nemak. AUTO21 Test Drive Competition, February 2012, 2nd place.

A program aiming at improving grain refinement was initiated. Use of Ti-B based master alloys and silicon demonstrated reduction in grain sizes of AZ91 alloy (Elsayed, IJMC, 2011; Lun Sin, AFS Trans. 2011, AFS Best paper award 2012). Reductions in grain size and inclusions were accompanied by substantial reduction of the hot tearing susceptibility and an increase in alloy strength. Invited paper of significance (Lun Sin, IMR, 2013).

Modeling was carried out using software developed in-house for predicting microstructural features such as grain size and dendrite arm spacing. This work brought out the need to determine the maximum nuclei density prior to its usage in macro-micro models. A heat transfer and fluid flow model for prediction of gas porosity and shrinkage with potential for application in various casting processes (sand, die and lost foam casting-LFC) was developed (Chen, AFS Trans., 1999, J. Mater. Eng. Perform., 2000, Venkataramani, Mater. Charact., 1995). This model is still valid and is used extensively in the Applicant’s current research. Pioneering analysis of hot tearing in permanent mould casting of magnesium alloys using neutron diffraction resulted in determining triggering levels of residual internal stress (Bichler, Canadian Journal of Physics, 2010). Solidification modeling was also used for estimating the interfacial heat transfer coefficient in complex casting systems for microstructural prediction and process design (Vandersluis, Trans. IIM, 2017).

Studies on fluidity and flow stoppage in hypereutectic Al-Si alloys elucidated fundamental understanding of the effects of eutectic and primary silicon morphologies under various casting parameters, and was extended to develop LFC parameters for B206 alloy (Dahata, AFS Trans, 2008). The process was optimized to enable the casting of magnesium periodic cellular materials (Ho, Scripta Mater., 2010).

Enabled advancing the exhaust manifolds (Silicon-Molybdenum Ductile Iron) to higher in-service temperature (800 to 1200°C) and high efficiency with minimal thermal oxidation (collaborative work with Wescast Industries). Just imagine non-stop truck transportation from Toronto to Houston with just periodic driver changes! Technology Transfer to Wescast. (Cvetnic et al., Canadian Metallurgical Quarterly, 2007)