The determination of residual stresses in coatings generally goes with the simultaneous determination of their elasticity constants. The main experimental methods used for that purpose are briefly reviewed and their advantages and limitations discussed: mechanical tests on self-bearing layers or on coated substrates, indirect physical methods.

The dynamical resonant technique in free bending mode used for the determination of constants of elasticity has been developed in view to characterize coated materials. It has first been applied to homogeneous single coatings from room temperature up to 1,100°C for thicknesses varying from 2 to 200 μm with the help of a formalism of composite beam. This formalism has then been extended analytically to three and four layers in order to characterize multicoated materials. For thermochemical treatments presenting a gradient of mechanical properties, a simplified n-layer model allows to estimate the modulus gradient as a function of depth.

We have developed an original method allowing to determine the elasticity constants of thin crystalline films deposited on substrates, which combines X-ray diffraction and in situ tensile testing. This technique has been successfully applied to measure the Poisson's ratio in tungsten thin films (150 nm) and molybdenum sublayers (8 nm) of a Mo/Ni multilayer. This paper gives the principles and experimental requirements for the Young's modulus determination.

Brillouin light scattering has been used to investigate the elasticity properties of polycrystalline smooth fine-grained diamond films having various diamond qualities. They have been deposited on titanium alloy Ti-6Al-4V by a two-step microwave plasma-assisted chemical vapour deposition process at 600°C. Taking advantage from the detection of a number of different acoustic modes, a complete elasticity characterization of the films has been achieved.

This paper describes a simple and efficient method to identify Young's modulus of thermally sprayed coatings. The mechanical method is based on the cantilever beam test, without the use of a strain gauge, combined with a finite element numerical modelling and optimization technique. The influence of coating roughness was taken into account in this work. Several types of coatings were tested and their Young's moduli were calculated. A sensibility analysis was also performed.

Transmission and reflection measurements using synchrotron radiation have been performed on a Ni sample submitted to tensile stress. For each studied crystalline plane, the strain was determined from spectral analysis of the diffracted beam, with a precision in the range of goniometric X-ray analysis. Apparent elasticity characteristics were then deduced assuming plane stress state on the surface and plane strain state in the bulk. The high elasticity modulus at the surface compared with the bulk one could be explained by a roughness effect or a lower yield stress near the surface.

This article studies the creep behaviour of the Ni/NiO system at 550°C under oxygen. Several phenomena of damage appear during the deformation in creep. These damages are in situ highlighted and separated with the help of the acoustic emission technique. These results are post-mortem confirmed by various standard techniques. Possible effects of interaction between the mechanisms of deformation and the degradation behaviour were also examined.

Precipitation hardening in lead-cadmium-calcium alloys is a two stage process: the first stage is a discontinuous hardening transformation without precipitation, the second stage is a discontinuous lamellar precipitation of Pb3Ca. In order to increase the mechanical and electrochemical properties of these alloys, we have studied the influence of minor additions of tin on the precipitation hardening behaviour of PbCaCd alloys, as this element is used to improve the electrochemical properties of positive battery grids. The objective was to investigate in a systematic manner the ageing and overageing behaviour of PbCdCaSn alloys in the case of two different structural states: as-cast condition, rehomogenized state.

The pencil edging diamond wheels used for lateral automotive glass grinding are composed of a mixture of metal powders (bond) and dispersed super-abrasive diamond grits (having a 100 μm average size). The metallic bond consists of a ductile alloy (sintered Ag+Cu+Ti powder mixture) and a hard skeleton (W and cast iron). The principal characteristics expected are a good wear resistance as well as a good cutting quality. In order to reproduce the industrial thermal cycle of the sintering manufacturing process in a traditional furnace, this cycle was simulated by dilatometric tests on green pellets of simplified metal powder mixtures. The aim was to determine the sintering behaviour of each component of the metallic bond.

p-methoxy benzylidene malonitrile (MN1) and p-hydroxy benzylidene malonitrile (MN2) were synthesized and tested as inhibitors for the corrosion of mild steel in molar HCl. We have found that both of them inhibit the corrosion. The maximum inhibition efficiency reached 100% for MN1 at 10-4 M and for MN2 at 10-3 M. Current-voltage curves indicated that malonitriles act as mixed type inhibitors. Their adsorption on the steel surface obeys to the Langmuir isotherm model. The effect of temperature on the corrosion behaviour of steel indicated that the inhibition efficiency of the two inhibitors decreases slightly with the rise of temperature in the range 298-338 K. The apparent activation energies for steel dissolution are greater than in the absence of inhibitors, which is consistent with a chimisorption mechanism.

Four different techniques have been used to study the thermal cycling effects on equiatomic Ti-Ni: Differential Scanning Calorimetry (DSC), Electrical Resistance measurements (ER), Internal Friction measurements (IF) and Vickers microhardness tests performed at room temperature. The measurements have been performed on well annealed samples, samples cold worked at room temperature and cold worked samples annealed at moderate temperatures.