Immersed wastewater pumps work in aggressive corrosive environments and physicochemical phenomena of corrosion and erosion take place at the liquid-solid interface. Due to the type of interaction between the two media when the basic metallic material is hydrophobic, corrosion phenomena can occur with the erosion due to the movement of the solid particles in the liquid. If the liquid is exposed to the hydrophilic base material, the corrosion phenomena occur in a laminar layer, having partial protection role. In this paper, the contact angle between the metals forming the pump components and the different corrosive media with different composition and pH was measured.

Galvanic corrosion occupies an important place among the corrosion techniques studies, especially because harbors and naval installations presents multiple components which are in direct contact with saltwater during operation time, such as: boats propeller - bronze, ship hull - carbon steel, rivets - steel, different types of protection shields - aluminum etc., thus metallic types combinations increase selective erosion depending on the metal position in the galvanic series. The galvanic corrosion prevention can be achieved by local cathodic protection with pieces of electronegative metal (zinc, magnesium) placed near the contacts or by inserting between these two metals of one or multiple high corrosion resistance materials to that specific medium. This paper presents an experimental study on different metal couplings in Black Sea water corrosion medium, in order to highlight the anodic (oxidation) or cathodic (reduction) protection of each metal during coupling.

Waste water is an aggressive environment for transport pumps to treatment plants. The pumps used are generally, immersion pumps and are made of various elements like, rotor, stator, housing, screws, flanges, springs, seals, etc. The construction elements of the pumps are made of various metallic materials, such as nodular cast iron, gray cast iron, low alloy steel, stainless steel, aluminum, bronze, brass, copper, etc. When immersed in waste water, the metals form galvanic series. The paper presents the galvanic corrosion analysis of the above-mentioned metals in case the corrosive environment is waste water with various compositions.

The carabiners are metallic links used to quickly connect the components of personal fall arrest equipment. Because these systems are used in corrosive environments, the carabiners must possess good corrosion resistance properties. In order to improve these properties, a phosphate layer was chemically deposited by converting on the carabiner material surface. This paper presents the microscopic analysis of the phosphated layer and the galvanic corrosion behavior of phosphated carbon steel, coupled to duralumin and initial carbon steel. Corrosion resistance has been studied for Black Sea water and fire extinguishing solution.

View the article online for updates and enhancements. Abstract. We have obtained, through the classic casting process, 3 highly chromium-based experimental alloys proposed for replacing the FC 250 classical cast iron in braking applications. Casting was carried out in an induction furnace and cast into moulds made of KALHARTZ 8500 resin casting mixture and HARTER hardener at SC RanCon SRL Iasi. It is known that the microstructure of the cast iron is a combination of martensite with a small amount of residual austenite after the heat treatment of the ingot. In the case of high-alloy chromium alloys, the performance of the material is due to the presence of M7C3 carbides distributed in the iron matrix Resistance to machining and deformation is based on alloy composition and microstructure, while abrasion resistance will depend on properties and wear conditions. IntroductionFriction between two dry surfaces in contact and moving relative to each other is known as Coulomb friction and even if it is a phenomenon that occurs several times a day the frictional force can only be estimated from previous experience and experimental results [1].In the case of braking systems (for any type of vehicle using braking systems) the contact surfaces are often covered with different materials to result in a sliding process and are not just two metallic materials sliding over each other. The metallic surface will be affected by abrasion, adhesion of compounds other than the base material, or deformation of the material during sliding, which will create metallic fragments of material as well as other particles [2].Any metal friction surface, even if it appears geometrically fine at a macroscopic level, is quite rugged on a microscopic scale, with a large distribution of roughness along it. An explanation of friction formation is the interaction of microscopic asperities of two surfaces, but when two such surfaces are forced to slide one on the other, it is very difficult to specify where and how contact occurs between them.Even if, from the point of view of an engineer, it can be assumed that a coefficient of friction between two surfaces, especially metallic, sliding one at the other, can be considered constant in the applicative work with the braking systems, it is very important to understand that this coefficient The friction is variable and it is very useful to understand why [4,5]. There are several reasons why the braking performance of a vehicle can change over time and any damage can be recognized by the user through a reduction in braking parameters such as distance or vehicle stopping time [6][7][8].Alloy cast iron with a high percentage of chromium are recognized as having a high wear resistance and have been widely used for wear-affected parts operating under extreme conditions. Exceptional wear resistance of Cr-rich castings results primarily from the high percentage of M7C3 carbides formed in the ferrous matrix with M = Fe, Cr and which have the role of preventing graphite formation and generally stabilize carbides [1...