Chromium nitride (CrN) films with Cr/N atomic ratios of 0.73–1.46 were prepared by reactive dc- magnetron sputtering with Ar as the sputtering gas and N2 as the reactive gas. The application of a negative bias voltage to the substrates and the decrement of the gas flow ratio of N2 to Ar (or FN2/FAr) promoted the growth of CrN films with preferred orientations of (200)+(220), high Cr/N ratios, and high densities. The functional hardness and compressive stress were highly dependent on the magnitude of the bias voltage and the Cr/N ratio that was adjusted by the FN2/FAr ratio during film deposition. The optimal energy conditions for ion impingement on growing CrN films with compact columnar crystal structure, high hardness, and enhanced tribological properties were studied with respect to the modulations of the bias voltages and the Cr/N ratios. The CrN films with high hardness and high wear resistance were synthesized in this study at low bias voltages of −(100–300) V and FN2/FAr ratios of 1–3.

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Barely Visible Impact Damage (BVID) can occur when laminated composite material is subject to out-of-plane impact loads and can result in a significant reduction in compressive strength. This paper reports on three compression tests of laminates optimised to maximise damage tolerance. Results from these tests were analysed using a semianalytical, fracture mechanics based method that predicts the strain below which laminated coupons containing BVID subject to axial compression will not fail. A further experiment was conducted on an artificially delaminated coupon in order to validate the modelling methodology. Results from one of the two optimised stacking sequences considered show an increase of over 40% in Compression After Impact (CAI) strength compared with a baseline configuration. Analysis of results has indicated that CAI strength is dependent to a great extent on damage morphology and stability of damage growth, both of which are functions of laminate stacking sequence.

A combination of uniaxial compression tests and Strip Model and Finite Element analyses of laminates artificially delaminated to create circular (±θ) sublaminates is used to assess the influence of fibre angle on the compressive strength of composite laminates.Sublaminates with 0° < θ < 40° are found to fail by sublaminate-buckling-driven delamination propagation and provide poor tolerance of delamination. This is a consequence of their relatively high axial stiffnesses, low sublaminate buckling strains, Poisson's ratio induced compressive transverse strains and extension-twist coupling which produces unexpected sublaminate buckling mode shapes. Sublaminates with 40° < θ < 60° are most tolerant to delamination; axial and transverse stiffnesses are minimal, formation of sublaminate buckles is resisted, high laminate buckling strains reduce interaction between laminate and sublaminate buckling mode shapes and extension-twist coupling is minimal. Sublaminates with 60° < θ < 90° are shown to produce varied tolerance of delamination. Sublaminate buckling is generally prevented owing to transverse tensile strains induced by mismatches between laminate and sublaminate Poisson's ratios but may occur in laminates with low Poisson's ratios.

The mechanical properties of Xe-implanted spinel and cubic zirconia surfaces, as determined by nano-indentation measurements, are distinct and the differences can be related to their microstructures. Upon Xe" ion irradiation at cryogenic temperature (120K), the Young's modulus of irradiated spinel increases slightly (a few percent) then falls dramatically until the modulus is only about 3/4 the unirradiated value. The maximum modulus occurs concurrent with the formation of a metastable crystalline phase of spinel. The subsequent elastic softening at higher Xe" doses is an indication of the onset of amorphization of the spinel. Xe-implanted zirconia surfaces behaves differently, in all cases showing almost no change in elastic modulus with increasing Xe" ion dose. This is consistent with microstructural observations of Xe-implanted zirconia crystals which, unlike spinel, show no change in crystal structure with increasing ion dose. The defected layer in zirconia due to ion damage simply thickens with increasing Xe" dose. This thickening may be a consequence of compressive stresses that form in the ion-implanted surface region. The hardness of both spinel and zirconia increases slightly for low Xe" ion doses. At higher doses, zirconia shows little change in hardness, while the hardness of the implanted spinel falls by more than a factor of two. The initial increase in hardness of both spinel and zirconia is probably due to point defect accumulation and the precipitation of small interstitial clusters, while the drop in hardness of spinel at high Xe* ion doses is due to the formation of an amorphous phase.