Improving tribological properties of cast Al-Si alloys through application of wear-resistant thermal spray coatings

Flame Spray Thermal Spray coatings are low-cost, high-wear surface-treatment technologies. However, little has been reported on their potential effects on cast automotive aluminum alloys. The aim of this research was to investigate the tribological properties of as-sprayed NiCrBSi and WC/12Co Flame Spray coatings applied to two cast aluminum alloys: high-copper LM24 (AlSi8Cu3Fe), and low-copper LM25 (AlSi7Mg). Potential interactions between the mechanical properties of the substrate and the deposited coatings were deemed to be significant. Microstructural, microhardness, friction, and wear (pin-on-disk, microabrasion, Taber abrasion, etc.) results are reported, and the performance differences between coatings on the different substrates were noted. The coefficient of friction was reduced from 0.69-0.72 to 0.12-0.35. Wear (pin-on-disk) was reduced by a factor of 103-104, which was related to the high surface roughness of the coatings. Microabrasion wear was dependent on coating hardness and applied load. Taber abrasion results showed a strong dependency on the substrate, coating morphology, and homogeneity

Networks on Silicon: Combining Best-Effort and Guaranteed Services

We advocate a network on silicon (NOS) as a hardware architecture to implement communication between IP cores in future technologies, and as a software model in the form of a protocol stack to structure the programming of NOSs. We claim guaranteed services are essential. In the THEREAL NOS they pervade the NOS as a requirement for hardware design, and as foundation for software programming

Miscible displacement flows in near-horizontal ducts at low Atwood number

International audienceWe study buoyant displacement flows with two miscible fluids of equal viscosity in the regime of low Atwood number and in ducts that are inclined close to horizontal. Using a combination of experimental, computational and analytical methods, we characterise the transitions in the flow regimes, between inertial and viscous dominated regimes, and as the displacement flow rate is gradually increased. Three dimensionless groups largely describe these flows: F r (densimetric Froude number), Re (Reynolds number) and Ø (duct inclination). Our results show that the flow regimes collapse into regions in a two-dimensional (F r, Re cos Ø/F r)-plane. These regions are qualitatively similar between pipes and plane channels, although viscous eAEects are more extensive in pipes. In each regime we are able to give a leading order estimate for the velocity of the leading displacement front, which is eAEectively a measure of displacement e±ciency