Abstract

A number of methods for measuring moisture transport properties of cementitious materials were compared in a series of experiments. Two OPC mortars with two water-binder-ratios were wet cured for six months and used to produce specimens as discs with different thicknesses and diameters."br /" The cup methods were easy to use, reliable and fairly rapid but need a stable, surrounding, CO2-free climate, however. Evaluating the fundamental potential PSI eliminates the derivation that adds to the uncertainty."br /" Steady-state moisture distribution measurements are very time-consuming and the RH-profiling is a delicate matter. Moisture contents are scattering. Sorption experiments are very easy to perform but difficult to evaluate, because of the peculiar moisture-dependency of the diffusivity Dw and the difficulties to estimate the equilibrium conditions. Initial uniform conditions are difficult to obtain for low w/c-materials, except to initial self-desiccation."br /" Sorption experiments in small steps are uncertain; the initial and final conditions are difficult to define properly. Document type: Report

Abstract

The main objective of the present work was to determine the influence of laser beam processing (LBP) on microstructure, microhardness, surface geometric structure, adhesion tests and tribological properties of coatings deposited on C45 carbon steel by the electro-spark deposition (ESD) process. The coatings were deposited by means of an EIL-8A. The laser processing was performed with an Nd:YAG, BLS 720 system. The studies were conducted using WC-Cu electrodes produced by the powder metallurgy route. The tests show the lasertreated electro-spark deposited WC-Cu coatings are characterized by higher adhesion and seizure resistance which come at the expense of lower microhardness. In addition, WC-Cu coatings after laser treatment had lower values of parameters of the surface geometric structure. The laser treatment process causes the homogenization of the chemical composition, structure refinement and healing of microcracks and pores of the electro-spark deposited coatings. Laser treated ESD coatings can be applied in sliding friction pairs and as protective coatings.