Corrosive Abrasive Wear Research Articles

Effect of graphene content on the tribological and corrosion behavior of high-speed-laser-clad high-entropy-alloy composite coatings

To repair oil drill pipe joints that have failed owing to dry wear and tribocorrosion, graphene-reinforced CoCrFeMo0.5NiTi0.5 high-entropy alloy composite coatings (HEACCs) were developed through high-speed laser cladding. The HEACC containing 1.5 wt% graphene exhibited dry wear and tribocorrosion rates that were 59.18 % and 32.20 % of those observed in the high-entropy alloy coating, respectively. The HEACC exhibited a corrosion current density of 2.475 × 10−7 A/cm2. The HEACC containing 1.5 wt% graphene underwent progressive damage during dry wear owing to the combined effects of abrasive wear, which created furrows; adhesive wear, which led to flaking; and oxidative wear, which formed oxide layers. During tribocorrosion, chloride ions exacerbated surface damage caused by hard abrasives and asperities, intensifying corrosive–abrasive wear interactions.

Correlating wear with the lubricant properties of heavy-duty diesel engine oils

Wear volumes were correlated with the lubricant properties of 11 used, heavy duty engine oil samples. The most important oil property in predicting wear volume is Total Acid Number, TAN. Here, the TAN value may be indicating ZDDP in its oxidised form and unable to participate in corrosive-abrasive wear. Low wear also correlates with mean soot particle size/circularity, which further suggests the abrasive aspect of this mechanism. Finally, low wear correlates with high calcium concentration in the fresh oil. This suggests a new wear reduction mechanism in which calcium from the detergent replenishes the iron within the ZDDP antiwear film.

Mechanical Properties of Arc Coatings Sprayed with Cored Wires with Different Charge Compositions

The mechanical properties (hardness, cohesion, and residual stresses) of arc coatings designed for operation under conditions of boundary friction and corrosive-abrasive wear are analyzed. The coatings were formed by arc spraying cored wires (CW) with different charge compositions (the content of carbon, aluminum, and boron in CW charge varied). It is shown that the hardness of the coatings increases with an increase in the carbon content in them up to 1 wt. %, and then decreased due to an increase in the content of residual austenite in their structure. The level of residual stresses of the first kind in such coatings increased by four times with an increase in the carbon content to 2 wt. %. The hardness of the coatings and the level of residual tensile stresses in them also increase with a decrease in the aluminum content in them. In this case, the cohesive strength of the coatings increased due to the implementation of aluminothermic reactions in the droplets of the CW melt during their flight and crystallization on the sprayed surfaces. However, then, with an increase in the aluminum content in the coatings of more than 2 wt. %, their cohesive strength decreased. The level of residual tensile stresses in coatings with a high content of retained austenite decreased after heat treatment (tempering) of the specimens. Sometimes, after tempering, these stresses even transformed into residual compressive stresses (in particular, under using CW C1.4Cr14Ni2). At the same time, the tempering of specimens with a predominance of ferrite in the coating structure increased the level of residual tensile stresses in them, which is due to the precipitation of finely dispersed carbides or borides. It has been shown that the addition of boron-containing components (ferrochromium-boron, chromium-boron) to the composition of the CW charge leads to a significant increase in the hardness of the coatings. Thus, an increase in the boron content in coatings from 0 to 4 wt. % leads to an increase in their hardness from 320 HV to 1060 HV. However, this is accompanied by an increase in tensile residual stresses in the coatings and a decrease in their cohesive strength.

IMPROVING THE RELIABILITY OF THE HYDRAULIC PART OF THE OILFIELD PUMP, TAKING INTO ACCOUNT THE SELECTION OF MATERIAL FOR THE SEAL ASSEMBLY

Many years of experience in the operation of oilfield equipment during underground well repair shows that ensuring the reliability and durability of the pumping units used is one of the main elements of the process chain, largely determined by the quality and performance characteristics of the friction units of the hydraulic parts of the pumps. It is known that high-pressure oilfield pumps used in the repair of oil and gas wells carry out various technological works, including cementing, hydraulic fracturing, acid treatment, washing sand plugs and other washing and squeezing operations. Parts of the hydraulic parts of the pumps are subjected to abrasive, corrosion-mechanical and corrosion-abrasive wear, which often leads to sudden failures, fraught with emergencies, additional costs and loss of time for unscheduled repairs. The article considers the possibility of increasing the reliability of plunger oilfield pumps due to the correct removal of the material of the sealing collars and improving the assembly scheme. It is also proposed to use the diffusion monotonic distribution as a model of failure to evaluate the reliability function of the selected best compression scheme. Since this distribution model is a more flexible function that better aligns qualified data, compared to the well-known two-parameter strict probability models. The results of the work have theoretical and practical prerequisites for assessing the reliability of field pumping units and may be useful for specialists working in this field

Method of Testing Rolled Tubular Products for Oilfield Pipes for Corrosion-Abrasive Wear

This paper describes the existing methods for determining the corrosion-erosion wear of materials, and describes a technique developed to assess the stability of oilfield pipes for corrosion-abrasive wear. The results of comparative tests on this method of steels 13HFA and St20 are presented.

Corrosive–Abrasive Wear Induced by Soot in Boundary Lubrication Regime

Soot is known to induce high wear in engine components. The mechanism by which soot induces wear is not well understood. Although several mechanisms have been suggested, there is still no consensus. This study aims to investigate the most likely mechanism responsible for soot-induced wear in the boundary lubrication regime. Results from this study have shown that previously suggested mechanisms such as abrasion and additive adsorption do not fully explain the high wear observed when soot is present. Based on the results obtained from tests conducted at varying temperature and soot levels, it has been proven that the corrosive–abrasive mechanism was responsible for high wear that occurred in boundary lubrication conditions.

ABRASIVE WEAR BEHAVIOR OF LOWER BAINITE DUCTILE IRON IN CORROSION MEDIA

The corrosion-abrasive wear behavior of lower bainite ductile iron was investigated by corrosionabrasive wear tests. The main factors of mass loss rate were analyzed. SEM and TEM were used to observe the worn surfaces. The strain-hardening effects beneath the contact surfaces were analyzed by microhardness profiles.The influence of load to corrosion resistance was researched by polarization curves. The results show that the main corrosion wear mechanism was corrosion mass loss and furrow wear. The roughness of worn surface, friction between sample and abrasive, depth of furrow all increased with the test load, which increased the corrosion-abrasive wear rate sharply. Meanwhile, the corrosion micro-cell formed along with the appearance of graphite ribbon and delamination at a higher load, which enhanced the corrosion rate rapidly, and the fracture of delamination resulting from plastic deformation fatigue was another critical factor of the increased mass loss. With the increase of test load, dislocation multiplication and pile-up took place in the retained austenite, which improved the wear resistance of material to some extent. However, the improvement was limited. The average mass loss rate was still increased from 0.16 g/(cm2· h) to 0.42 g/(cm2· h) with the increase of test load; the corrosion current density(icorr) was enhanced from 0.56 m A/cm2 to 5.62 m A/cm2 along with the increase of roughness. In addition, the mass loss curves of lower bainite ductile iron were divided into three stages: point contact wear(initial stage), surface contact wear(transition stage) and fatigue wear(stability stage).

Corrosion-abrasion wear resistance of 28%Cr white cast iron containing boron

The influence of boron additions (0–0.6 wt.%) on the corrosion resistance and corrosion—abrasion resistance of 28%Cr white cast iron has been studied. Experimental results show that in static corrosion tests the corrosion rate (pH = 1) increases with increasing boron content, but its corrosion resistance is much better than that of 15%Cr cast iron. The 28%Cr iron is passivated when pH > 3. In the corrosion-abrasion wear process there exists a certain correlation between corrosion-abrasion wear resistance and corrosion resistance. When pH = 1, boron increases the weight loss during corrosive-abrasive wear, but boron abruptly decreases the weight loss when the pH reaches 3. It is considered that corrosion predominates when pH = 1 and abrasive wear predominates when pH > 3 in the corrosion—abrasion wear process. In the latter case, being able to increase the hardness of both carbide and matrix, boron can effectively increase the corrosion—abrasion wear resistance of the iron.

Corrosive-abrasive wear of porcelain enamel coatings

in the production of enamelled chemical equipment, were selected. The enameling of the specimens (Fig. i) was done in four layers, two layers of ground-coat and two layers of cover-coat enamel (using the slip method normal in the industry). The total coating thickness of the working surface (the surface immersed in the test medium) of the specimen was 0.6-0.8 mm. The temperature range of the tests was 15-50~ (deviation from the specified temperature 176 The compositions of the corrosive media were H20 distillate (pH 7) + particles of silicon carbide SiC to GOST 3647-80 in a 5:12 volume ratio and 5%CHoCOOH solution + particles of silicon carbide (pH 2.4) in the same volume ratio. The rate of rotation of the specimen was 96 rpm. The eccentricity of the axes of rotation of the specimen and the drive was 12 mm. The corrosive abrasive wear of the tested enamel coatings was determined as the loss of weight of the coating per unit of area of its working surface per unit of test time. The -- ,~ ~ ../,"/,.