Papers by Keyword: Corrosive Wear

Abstract: National standard high chromium cast iron contains 26% chromium by weight (Cr26). A new type of Super High Chromium Cast Iron (SHCCI) has been developed with chromium content of about 37% by weight. This paper examines the microstructure of SHCCI using SEM and XRD. The hardness and toughness of SHCCI was studied and the corrosive wear properties of SHCCI were also examined using an MCF-30 type erosion abrasion tester under H3PO4 media. The results show that, the microstructure of SHCCI is composed of M7C3 and M23C6 carbides, martensite matrix and residual austenite matrix. With proportionately greater carbon content, the hardness of SHCCI will first increase and then decrease, while the toughness and corrosive wear properties will decrease gradually SHCCI’s corrosive wear performance was significantly better than that of Cr26 cast iron. The maximum wear capacity of SHCCI is three times higher than that of Cr26 cast iron.

Abstract: The MMS-2B wear machine was used to study abrasion wear of work rolls in cold rolling by simulating emulsion cooling during the cold rolling process. The work roll materials used were 4%Cr, same as those in industrial production. The surface SEM scanning photographs were taken every 30 minutes until the friction experiment finished, and erosive appearance of emulsion on the work roll surface could be seen in the photos. The corrosive wear of the work roll surface is discussed. Findings show that the main causes of stress corrosion and pitting corrosion are uneven microstructure on the work roll surface and a large number of dislocation accumulations, which form microscopic cells. Water in steel rolling emulsion is the main conductive medium of electrochemistry reaction, and this intensifies the corrosive wear.

Abstract: The corrosion behavior during friction of refined bio-oil by distillation process was evaluated by high frequency reciprocating test rig. Both scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) were used to investigate the morphology and active elements contents on the rubbed surface on steel disk. The chemical structures of the oils and the topography and surface roughness of the wear scar were also studied by FTIR and surface roughness tester as well, respectively. The experimental results showed that corrosion behavior of bio-oil was improved after refining since the wear depth was 3.75µm and the worn surface roughness was 0.172µm, while they were 12.5µm and 0.217µm before refining. It was concluded that corrosion degree of worn surface was decreased after the bio-oil was refined, which was ascribed to the decrease of the acidic component content after the refining process.

Abstract: W-Mo and W-Mo-N surface-modified layers on Ti6Al4V alloy were obtained using a double glow plasma surface alloying technique. The morphology, microstructure, and chemical composition distribution of the modified layers were analyzed by scanning electron microscope, Xray diffraction, and glow discharge optical emission spectrometry. The hardness and toughness of the modified layers were measured using a micro-hardness tester, and dynamic repeating press equipment. The wear resistance in ambient air and the corrosive wear resistance in NaCl solution were evaluated using a ball-on-disk wear tester. The results show that W-Mo and W-Mo-N surface modified layers are composed of the alloying layers which vary in composition and phase form along the depth. A microhardness gradient was observed in the modified-surface layers. The surface hardness of the W-Mo-N and W-Mo modified layers was 25.3 and 14.2 GPa, which is seven-fold and 3.9-fold harder than the Ti6Al4V substrate, respectively. W-Mo and W-Mo-N surface-modified layers significantly improved the wear and corrosion resistance of Ti6Al4V. It seems that the wear resistance of W-Mo and W-Mo-N surface-modified layers in NaCl solution is better than that in ambient air owing to the strong lubricating effect of NaCl solution and the excellent corrosion resistance of the modified layers.

Abstract: There were a large of the flowing through parts such as valve and slurry pump in production line of aluminum oxide. Because they were grinded and corroded by the strong alkalinity thick liquid of bauxite particles, their life was extremely shorten. So, the ZrO2/Ni60 composite coatings were manufactured by laser cladding. According to distribution state of particle phase, a set of optimum technological parameters recommended was 10.45g/min(powder feeding rate), 2.4mm/s(laser beam scan velocity), 2kW(laser power) and 60mm(defocusing amount), 5% ZrO2 (weight ratio). The M-200 abrasive tester was used to investigate the tribological behavior of the coating in strong alkaline solution (40%NaOH). As results showed, the friction and wear mechanisms of the coatings would be changed with test work condition, and the generating or dissolving of the protective passivity films on the surface of the friction pair was a dynamic state process, even as rotational speed was the high-velocity and load was the mediate load, existence could take effect in anti-wear of reinforced coating.

Abstract: In continuous hot dip galvanizing, serving parts working in the molten zinc, such as sink roll, sleeves, etc. tend towards degradation and failure due to corrosion and wear. In this paper, corrosive wear performance of several materials, such as boronized，H13，Co-based alloy and Fe-based alloy coupled with Si3N4 is evaluated with the aid of a self-made test machine of block-column sliding wear. Moreover, the corrosive wear mechanism is analyzed. It has been found that these materials suffered not only considerable wear, but also the corrosion of molten zinc. For boronized layer, the wear is the main reason to cause the failure of work parts under the act of the corrosive wear. For H13, the interaction between corrosion and wear plays a very important role on its failure. For those alloys with bad corrosion resistance such as Co-based alloy and Fe-based alloy, both corrosion of solid solution and wear of intermetallic compound act on their failure at the same time. However, the rate of wear shows no obvious relation to the hardness although wear performance is important. The failure greatly lies on the ratio of the hardness of corrosion products to matrix.

Abstract: TiO2 films were fabricated on stainless steel (SS) substrate by plasma surface alloying and thermal oxidation duplex process. Composition and microstructure of the films were characterized using glow discharge spectrometer (GDOES), X-ray photoelectron spectroscopy (XPS) and XRD. Results reveal that the TiO2 films are dense, homogeneous and existed in a complete anatase structure. Both Ti and O elements show gradient distribution in the films. The wear behavior of TiO2 films in Hanks’ solution indicates that the films display much better wear resistance and antifriction performance than that of SS substrate. Electrochemistry noise tests indicate that the TiO2 films effectively retard the local pitting and crevice corrosion of the SS substrate.

Abstract: Thermal spraying is one of the most variable and diverse surface coating techniques concerning materials to be processed as well as possible geometries to be coated. The group of thermal spray processes covers a large parameter field to combine nearly each coating with each base material. Thermally sprayed coatings can be applied very evenly and therefore allow to be applied on final-shaped components. Otherwise, if further treatment or finishing is necessary, thermal spray coatings can be processed by grinding or even milling. Masking during the coating process permits the selective coating of specific surface parts or the application of required geometrically structures, e. q. conductor structures. The main application field of thermal spray coatings is the (combined) wear and corrosion protection of selected component parts.

Abstract: This paper analyses the state of knowledge on the range of analytic modeling of wear in conditions of corrosive and mechanical interactions. So the achieved knowledge has allowed us to formulate our own complex calculation algorithm. Based on that, the authors have elaborated a computer program enabling a full simulation of corrosive and mechanical wear of rough surfaces in pin – on – disc situation. The results of simulations and experimental tests are given in the paper.