Abstract: In this present work, TiN films with various thicknesses (from 0.3 μm to 2 μm) were deposited by DC reactive magnetron sputtering on Ti6Al4V substrates. The evolution of texture and microstructure were studied by X-ray diffraction and Scanning Electron Microscopy, respectively. The XRD characterization indicates that the preferred texture of TiN films is changed from (111) to (100) with increasing the film thickness. The microstructure characterization shows that their microstructure transform from continuous into columnar with increasing the TiN film thickness. It is considered these results are arised from the change of overall energy including surface energy and strain energy with the film thickness. The hardness of TiN film increases with increasing the film thickness.
Abstract: In cookware manufacturing industry, spray coating process plays an important role both in function and appearance quality of a product. Typically, Teflon (PTFE) is used for interior coating to increase corrosive and nonstick. Practically, nozzle size and spray time are crucial variables to dry file thickness (DFT) in the process. In mass production, a product is mounted on a rotating spindle which installed on the conveyor and moves pass the spray guns. Thus, the rotating speed is also a potential variable to the DFT. Thus, the objective of this paper is to explore a relationship of these abovementioned three variables i.e. nozzle size, spray time, and rotational speed to dry film thickness After that the optimal condition such that the required DFT is met will be determined. To achieve this goal, the experimental design technique including analysis of variance (ANOVA) is employed in this study. It is found that each of the three variables affects the DFT. The higher of spray time, nozzle size, and rotational speed, the more coating thickness onto the part.
Abstract: This paper presents results of experimental investigation to evaluation the effects of compressive strength on flexural behavior of steel fiber-reinforced concrete (SFRC). For this purpose, normal and high strength SFRCs with two different fiber volume fractions of 0.5 and 1.0% were prepared. Compressive strength, modulus of elasticity, flexural strength and toughness were measured with tests on SFRC cylinders and prisms. Test results indicated that steel fiber volume fraction significantly affects the flexural strength and toughness of SFRC. However, the high strength SFRC showed reduction in flexural toughness compared with the normal strength SFRC. It can be concluded that flexural behavior of SFRC depends on both compressive strength and fiber volume fraction.
Abstract: This paper deals with the experimental testing and theoretical analysis of the flexural load-bearing capacity of I-shaped pillars in noise barriers made of reinforced concrete, prestressed concrete and prestressed steel fiber reinforced concrete. The pillars were loaded as a cantilever under a flexural load, which corresponds to their actual loading when the effect of wind on the panels of the noise barrier is taken into account. For the purpose of the present research, three specimens of I-pillars were tested. The results of the experimental loading tests, as well as the calculated results and the comparison between them, are herein presented.
Abstract: Cracks were observed when the magnesium silicate hydrate gel cement (prepared by 40% MgO/ 60% silica fume) was dried. This drying cracking is believed to be caused when unbound water evaporates from the binder. The shrinkage upon forced drying to 200 °C of mortars made up from a reactive magnesium oxide, silica fume and sand was measured using dilatometry. The magnitude of the drying shrinkage was found to decrease when more sand or less water was added to the mortars and can be as low as 0.16% for a mortar containing 60 wt% sand and a water to cement ratio of 0.5, which is of a similar order of magnitude as observed in Portland cement based mortars and concretes. A simple geometrical interpretation based on packing of the particles in the mortar can explain the observed drying shrinkages and based on this analysis the drying shrinkage of the hydration products at zero added solid is estimated to be 7.3% after 7 days of curing.