Surface coating played a role of material mechanical property, CrN and CrAlN coatings were deposited on H13 steel to improve its tension and fatigue performances. The morphologies, phases and nanomechanical properties of obtained coatings were analyzed using a scanning electron microscope (SEM), X-ray diffraction (XRD), and nanoindentation tester, respectively. The effects of CrN and CrAlN coatings on the tensile and fracture performances of H13 steel were investigated by tensile and fatigue tests, and the fracture morphologies were observed to analyze the fracture mechanism. The results show that the CrN and CrAlN coatings improve the tensile properties of H13 steel, the area work of CrAlN coated sample is the largest among the three kinds of samples. The fatigue life of CrN and CrAlN coated samples is 1.52 × 105 and 1.70 × 105, respectively, higher 1.01 × 105 than the uncoated sample, the CrN and CrAlN coatings enhance the fatigue life of substrate. The crack initiation and propagation of coated samples are suppressed by the coatings with the high hardness and elastic modulus, which improve their fatigue performances. Hosted file0825) effects of crn and craln coatings on fa.doc available at https://authorea.com/users/ 354108/articles/477757-effects-of-cathodic-arc-ion-plated-crn-and-craln-coatings-ontensile-and-fatigue-performances-of-h13-steel

This study focuses on the thermo-mechanical properties of mortar in the retrofitting cover of additional reinforcement for existing concrete structures. In addition, the residual mechanical properties of high strength mortar incorporating polypropylene fibers subjected to the effect of fiber length and the elevated temperature were investigated. Several experiments were conducted to determine the optimum mixture proportions of high strength mortar incorporating polypropylene fibers which had a slump-flow of 25-30 cm, compressive strength of 50 MPa or higher, and flexural strength of 4-8 MPa. Subsequently, an experiment was conducted by using high-strength mortar-blended polypropylene fibers with a length of 2 cm, and the ratio of fiber length to the diameter of cylinder mortar-specimens was 0.4. The experimental parameters were the weight volume of fibers (0 %, 0.5 %, 1 %, and 2%) and the heating temperature (100, 200 and 300 °C). The effect of the mixing parameters, including polypropylene length on compressive strength, slump-flow and the flexural strength of mortar were discussed. It is evident that fiber in the mortar cover influenced the initial and residual mechanical properties, such as elasticity, compressive strength, and Poisson's ratio, of the mortar.