Using traditional weight-loss tests, as well as different electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy), we investigated the corrosion-inhibition performance of 2,2′-(1,4-phenylenebis(methanylylidene)) bis(N-(3-methoxyphenyl) hydrazinecarbothioamide) (PMBMH) as an inhibitor for mild steel in a 1 M hydrochloric acid solution. The maximum protection efficacy of 0.0005 M of PMBMH was 95%. Due to the creation of a protective adsorption layer instead of the adsorbed H2O molecules and acidic chloride ions, the existence of the investigated inhibitor reduced the corrosion rate and increased the inhibitory efficacy. The inhibition efficiency increased as the inhibitor concentration increased, but it decreased as the temperature increased. The PMBMH adsorption mode followed the Langmuir adsorption isotherm, with high adsorption-inhibition activity. Furthermore, the value of the indicated that PMBMH contributed to the physical and chemical adsorption onto the mild-steel surface. Moreover, density functional theory (DFT) helped in the calculation of the quantum chemical parameters for finding the correlation between the inhibition activity and the molecular structure. The experimental and theoretical findings in this investigation are in good agreement.

The function of the axle drive shaft is to transfer the engine torque from the gearbox or differential gear to the wheels. It must also endure for all dynamic loads resulted from variations in angle or length during driving from contact the vehicle tire with road. Most problems with the axle drive shaft manifest themselves in the form of knocking noises when driving around tight corners, accelerating, or when the suspension is being compressed and extended where the drive shaft becomes weakened and more subject to stress failure due to dynamic torsion, tensile, shear, and compression. This work consists of effect of heat treatment type applied to the steels CK45 on the resulted behavior of the fatigue and toughness and study of these heat treatments on the microstructure and micro-hardness across the specimens depth. Where this heat treatable alloy usually used in drive-shafts in vehicles which exposed to a dynamic loads and the goal is to investigate the best relation between heat treatment and the service conditions. However, microstructural characterization and microhardness measurements revealed that the shaft belongs to medium carbon steel contains ferrite and pearlite, measuring the toughness for four heat treatments to obtain the best case and measuring the fatigue life of quenching case has better life compared to other cases. The oil quenching gives best toughness value of 30 Kj/m2 and the worst value obtained for as received one giving 7 Kj/m2 and the maximum fatigue life under stress of 375 MPa belonged to oil quenching treatment and it was 75000 cycles to failure while the as-received alloy reported 2000 cycles at failure. The S-N curve of the four cases based on Basquin formula with correlation factor (R2) close to one. And the water quenching steel alloy recorded higher curve component to other cases.

The present work is focused on diffusion bonding between pure titanium and austenitic stainless steel( AISI 316) using interlayer of pure copper foil in vacuum atmosphere of ( 1.5 x10-5 mbr.) at different temperatures (850,900,950 and 990) Co for diffusion times of (20,30,40,50 and 60 min.) under different pressures (1.5,2,3 and 4) Mpa. Many tests and inspections: tensile shear and microhardness tests, also SEM EDS and X-ray diffraction techniques were utilized to characterize the bonded joints. Tensile shear test results showed that the maximum shear strength of diffusion bonded joints was (96.34) MPa at 950°C, pressure 3Mpa and 50 min. with an efficiency of joint (75%) and maximum diffusion depth of (88 µm) The maximum micro hardness of (338.6 Hv )was obtained in the copper interlayer metal compared with the base metals(stainless steel and titanium) due to formations of brittle intermetallic compounds. The EDS and XRD analysis results confirmed the formation of different intermetallic compounds [FeTi, ( Cu + Ti37Cu63Fex ), TiCu, Ti2Cu, Ti3Cu4,]. The surface fracture topography showed that fracture is located at the bright brittle intermetallic compound phase(Ti3Cu4) which was 85% of the fractured area and 15% was at the (Ti2Cu)dark region.

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The coated surfaces first layer Ti and second layer TiO2 as coating Nanostructured thin films of using DC sputtering on structural steel (AISI l018) and study characterization of coating SEM/EDS inspection shown a clearly perfect incorporation of layer by dc sputtering a granular structure of the layer with a variable hemisphere’s forms varied from 33 to 46 nm in size. X-XRD test complete for specimen indicates was found anatase phase titanium dioxide, the resulted coating layer of the target of Ti powders gives different morphology from the Ti layer alone The Specimens roughness average of coated Ti and TiO2with respectively was 4.831nm, 7.93 nm. Found that titanium layer will show a major part in increasing the bonding with improving the bond between the substrate steel AISI (1018) and the titanium oxide layer. The Vickers hardness increases when the coating with a layer of titanium with an oxygen content of ceramic layer is formed from 192.3 HV to 227 for Ti as well as important increase was detected in the Tio2 coating to 240 HV. In addition, Ti and Tio2 thin layer considered as a good barrier for hydrogen permeation through steel structure especially at cathode protection in pipelines.