Hydroabrasive Resistance Research Articles

Performance of Ni-Based Coatings with Various Additives Fabricated by Cold Gas Spraying

The complexity of the operating conditions in oil fields requires the development and use of materials with unique properties. This paper presents the study results for nickel-based coatings fabricated by cold gas spraying. In this study, compositions based on Ni, Ni-Cu, Ni-Zn, Ni-Al2O3/TiC coatings applied to low-alloyed steel bases were investigated. Corrosion resistance was studied by means of electrochemical autoclave testing in simulated oilfield conditions. Hydroabrasive resistance was studied using a unique testing bench. Scanning electron microscopy mappings, microhardness testing, and adhesion testing were used to correlate the results of the tests with the structure, continuity, and porosity of the studied coatings. All the studied coating specimens had a sufficiently high adhesion. The Ni-Zn coating exhibited the lowest corrosion resistance and high hydroabrasive resistance. The Ni-Cu coatings exhibited a high degree of corrosion. The Al2O3/TiC additives gave ambiguous results with respect to the studied properties. Thicknesses of 40–60 microns provided acceptable performance for the studied coatings. Thus, varying the chemical composition the thickness of coatings allows optimal qualities to be obtained for Ni-based coatings made by cold gas spraying for use in the oil and gas industry.

Investigation of hydroabrasive resistance of internal anti-corrosion coatings used in the oil and gas industry

Anti-corrosion coatings are commonly used in the oil and gas industry to protect the inner surface of pipelines. Most of coatings have a polymer base and can effectively prevent the negative impact of the transported fluid. Existing standards allow to evaluate the quality of coatings and their durability in the anticipated operating conditions. The evaluation of the abrasive resistance of coatings usually limited to comparative tests on a Taber abraser. This paper presents the results of hydroabrasive resistance study of coatings using nonstandard technique. Comparative test results of various polymer (FBE), thermally sprayed coating and silicate coatings are obtained. The ways of modifying test method are proposed.

Investigation of Hydroabrasive Resistance of Titanium Alloy VT6S Used for Centrifugal Compressor Wheels

Investigation of Hydroabrasive Resistance of Titanium Alloy VT6S Used for Centrifugal Compressor Wheels

The Use of Complex Additives for the Formation of Corrosion- and Wear-Resistant Epoxy Composites

The corrosion resistance and hydroabrasive resistance of the developed epoxy composite coatings are investigated in this paper. The analysis of the penetration index change after τ = 50–150 days of immersion in a water medium and 10% sulfuric acid solution is carried out. The optimal ratio of the modifier and nanodispersed (Si3N4, Al2O3, AlN, and TiN) and fibrous (viscose, polyamide, matka silk, rong, and cashmere) fillers in the epoxy binder is determined. It was allowed to slow down the process of electrochemical reaction on the metal surface. The penetration of aggressive media in such a coating during the time t = 150 days is 0.8–2.8%. It is 1.5–2 times lower than the similar indexes of the initial epoxy matrix. The rational combination of the fibrous filler (wool, acrylic PAN, and cashmere), modifier, and nanodispersed (Si3N4, AlF3, IH, and ZrH) filler in the epoxy binder is found, which allows to provide optimum indexes of wear rate. The wear rate under the action of a hydroabrasive of such a coating is I = 0.20%, which is 4 times lower than the similar indexes of the initial epoxy matrix. The wear mechanism of such coatings is caused by the physical and mechanical processes of microcutting and plastic deformation of the surface layer of the material.

Гідроабразивна стійкість композиційних газотермічних покриттів на основі інтерметалідів

Гідроабразивна стійкість композиційних газотермічних покриттів на основі інтерметалідів

Hydro-abrasive resistance of engineered cementitious composites with PP and PVA fibers

The abrasion resistance of engineered cementitious composites (ECC) under the impact effect of water and waterborne erodent materials was experimentally investigated in this research. The abrasion tests were conducted using the water jet method with graded sand used as the erodent material and square ECC plate specimens with 200 mm side length and 50 mm thickness. Fixed basic ECC mixture was adopted for all test specimens but with variable fiber type and fiber content. PP and PVA fibers were used with four volumetric contents of 0.5, 1.0, 1.5, and 2.0%, in addition to similar specimens without fiber. The variables that were investigated using the PP and PVA-based ECC were the fiber content and the age. The effect of the inclination of the specimens with respect to the water jet was investigated using PP-based ECC only. The test results showed that both types of fiber enhanced the abrasion resistance and decreased the abraded weight. The percentage abrasion resistance enhancement was higher for specimens incorporating higher fiber contents. The test results also showed that the abrasion weight loss decreased as the inclination of the exposed surface with horizon increased.

A new methodology for hydro-abrasive erosion tests simulating penstock erosive flow

Hydro-abrasive resistance is an important property requirement for hydroelectric power plant penstock coating systems used by EDF. The selection of durable coating systems requires an experimental characterization of coating performance. This can be achieved by performing accelerated and representative laboratory tests. In case of severe erosion induced by a penstock flow, there is no suitable method or standard representative of real erosive flow conditions. The presented study aims at developing a new methodology and an associated laboratory experimental device. The objective of the laboratory apparatus is to subject coated test specimens to wear conditions similar to the ones generated at the penstock lower generatrix in actual flow conditions. Thirteen preselected coating solutions were first been tested during a 45 hours erosion test. A ranking of the thirteen coating solutions was then determined after characterisation. To complete this first evaluation and to determine the wear kinetic of the four best coating solutions, additional erosion tests were conducted with a longer duration of 216 hours. A comparison of this new method with standardized tests and with real service operating flow conditions is also discussed. To complete the final ranking based on hydro-abrasive erosion tests, some trial tests were carried out on penstock samples to check the application method of selected coating systems. The paper gives some perspectives related to erosion test methodologies for materials and coating solutions for hydraulic applications. The developed test method can also be applied in other fields.

Abrasion resistance of concrete made with micro fibers and recycled granulated rubber

Durability of concrete engineering structures in most part depends on the resistance of their surface to mechanical abrasion. The paper presents the results of experimental test of performance of concretes made with micro fibers and recycled granulated rubber in fresh and hardened state, as well as the comparative analysis of wear grinding resistance and hydroabrasive resistance of concrete. Six batches of concrete were made for the tests: reference concrete, concrete with partial replacement of fine river aggregate with recycled granulated rubber, two batches with the addition of polypropylene fibers (monofilament and fibrillated) and two batches of concrete with addition of steel hook ended fibers (short - having length 30 mm and long - having length 50 mm). It was found that the addition of micro-reinforcement or recycled rubber contributes to the increase of concrete wear grinding resistance and hydro-abrasive resistance. There is a difference in the abrasive resistance depending on test method.

Hydro-abrasive resistance and mechanical properties of rubberized concrete

Hydro-abrasive resistance and mechanical properties of rubberized concrete

Erosive and hydroabrasive resistance of hardfacing materials

The erosive and hydroabrasive wear are very intensive degradation processes of the surface layers of the metallic materials. The wear resistance is influenced by the working conditions and the material parameters like hardness and microstructure. These parameters of the hardfacings are determined by the technology of building-up and the chemical composition of the overlay. The present knowledge of material parameters and their influence on the wear by particles does not allow to predict lifetime of machine parts. Therefore, it is necessary to test candidate materials experimentally. The laboratory tests will enable the optimum selection of the chemical composition of weld deposits and the technology of hard surfacing. The hard deposits containing borides and carbides have improved erosive and hydroabrasive wear resistance. Tribological behaviour of this hard layers have been tested by sand-hydroblast apparatus EO-2 and centrifugal erosion tester CUK-3. The determination of the conditions of optimum application these materials in industry for improving performance and longer service life of various machine parts is the technological aim of our project in the frame of research programme COST 516.

Protection of elements of the water passage of turbines from hydroabrasive wear

1. The hydroabrasive resistance of structural steels does not provide the necessary reliability of turbines operating on sediment-transporting rivers. 2. Case-hardening of structural steels and resistant protective coating are used for increasing the reliability and life of parts of the flow passage. 3. During actual service the effectiveness of casehardening decreases by half compared with laboratory tests, which is explained by the insufficient thickness of the protective layer. It is not advisable to use this type of surface protection for turbines with a high intensity of hydroabrasive action, since it is impossible to restore the protective layer under hydrostation conditions. 4. Two types of protective coatings have the highest priority: protective electrode hard surfacing on a cobalt base, for instance, TsN-2, which while providing a high wear resistance of the surface, E greater than 3, permits making a protective layer of the required thickness 3–5 mm and repairing the flow part of the turbine directly at the hydrostation; synthetic polyurethane-based compositions making it possible to completely cover the runners with a coating thickness of 1.5–2 mm. Destroyed polyurethane coatings can be restored directly at the hydrostation.

Hydroabrasive resistance of plasma coatings of self-fluxing Ni-Cr-Si-B alloys in chloride solutions

To increase the wear resistance of a machine the method of plasma spraying of self-fluxing Ni-Cr-Si-B wear-resistant alloys is used. In tests, self-fluxing alloys Kh 15N 70M5S5R5 (plus others) were sprayed on 12 Kh 18NIOT steel. Investigations were made on a type PV-12 machine, the hydroabrasive media being tap water and solutions of sodium chloride. The tests showed that three coatings possess high resistance to hydroabrasive action. The angle of incidence has a great influence on the resistance. An increase in the angle results in significant reduction of wear, the minimum wear registered at angle of incidence 60 /sup 0/. The influence of corrosion-active media and chlorine solutions was also tested. Compared to hydroabrasive, corrosive-active media have a significant influence on weakening surface layers in steel. This data was obtained by experiment under conditions of potassium fertilizer production. The use of Kh15 70M5S5R5 coating is recommended as a hydroabrasive resistant in chlorine solutions.

Corrosion and hydroabrasive resistance of materials under conditions of potassium chloride production by crystallization

Corrosion and hydroabrasive resistance of materials under conditions of potassium chloride production by crystallization