Intensive Abrasive Wear Research Articles

Influence of WC-Co knifes pre-treatment with drag finishing method subjected to tool coatings deposition on blunting process

ABSTRACT This paper details the analysis of the micro geometry in modified tools coated with the nano multi-layer TiN/AlTiN obtained by the PVD method. In standard replaceable cutting blades made of WC-Co before deposition, the radius of the blade rounding was increased from about 4 µm to about 13 µm using the drag finishing method with usage of OTEC company device. Next, the tools coated with the multilayer nano-coating TiN/AlTiN were subjected to blunting process. Mentioned above procedure was carried out on a standard 18 mm thick chipboard, assuming the blunting criterion (maximal tool wear on clearance face) Vbmax = 0.2 mm. In addition, previously blunted tools (modified and unmodified) were subjected to a detailed geometric analysis on a contact profilometer. Results show significant differences in the changes of various geometric parameters, in particular in the coefficients determining the asymmetry of the edge roundness denoted with letter K. Especially analysis of changes that concerns coefficient KR based on loss of cutting edge from rake face in comparison to clearance face suggests more intensive abrasive tool wear on rake face. Based on durability tests it can be supposed that changes in values of asymmetry coefficients in general described with letter K can decide about tool life.

Carbides of transition metals: Properties, application and production. Review. Part 2. Chromium and zirconium carbides

The properties, application, and methods for producing chromium and zirconium carbides are considered. These carbides are oxygen-free refractory metal-like compounds. As a result, they are characterized by high values of thermal and electrical conductivity. Their hardness is relatively high. Chromium and zirconium carbides exhibit significant chemical resistance in aggressive environments. For these reasons, they have found application in modern technology. Chromium carbide is used mainly as component of surfacing mixtures to create protective coatings that resist intensive abrasive wear, including at elevated temperatures (up to 800 °C) in oxidizing environments. This compound is also used in the manufacture of tungsten-free hard alloys and carbide steels. Chromium carbide, along with vanadium carbide, is used as a grain growth inhibitor in WC – Co hard alloys. Powdered zirconium carbide can be used to polish the surface of items made of ferrous and non-ferrous metals. The properties of refractory compounds depend on the content of impurities and dispersion (particle size). To solve a specific problem associated with the use of refractory compounds, it is important to choose the right method for their preparation, to determine the permissible content of impurities in the initial components. This leads to the existence of different methods for the synthesis of carbides. The main methods for their preparation are: synthesis from simple substances (metals and carbon), metallothermal and carbothermal reduction. Plasma-chemical synthesis (vapor-gas phase deposition) is also used to obtain carbide nanopowders. A characteristic is given to each of these methods. Information on the possible mechanism of the processes of carbothermal synthesis is presented.

Aspiration of loading iron ore pellets into railway wagons using a ceramic filter.

Loading of iron ore pellets into railway wagons at mining and processing enterprises is accompanied by the formation of a significant amount of suspended iron-containing highly abrasive particles. The shortcomings of existing aspiration systems currently used to reduce the negative impact on the environment are considered. It is demonstrated that existing wet cleaning devices, as a rule, do not meet the requirements of sanitary standards for emissions into the atmosphere. Tubular cloth filter of dry-cleaning devices is subject to intense abrasive wear of the iron ore dust captured, which leads to a violation of sanitary standards for emissions of solid particles into the atmosphere. The results of pilot plant tests of a ceramic filter installed in the existing aspiration system for loading iron ore concentrate into railway wagons are described. The aerodynamic resistance of the ceramic filter is determined, as well as its technical and economic indicators. It was found that when replacing the tubular cloth filter with a ceramic pulse filter, a decrease in the residual dust concentration from 72 to 4 mg/m3 was achieved. The efficiency of cleaning the aspiration flow in a ceramic filter is 17.8 times higher than this indicator in the existing tubular filter. The replacement of cloth filter elements with ceramic ones in the body of the existing filtration system of the aspiration system for loading iron ore pellets into railway cars will reduce the gross emissions of iron-containing dust into the atmosphere from 47 to 1.9 tons/year. When replacing cloth filter elements with ceramic ones, the total fee for the negative impact on the environment within and above the MPE will decrease from 130 thousand roubles/year up to 85 thousand roubles/year. In addition, the return of dust material to production will save at least 0.5 million roubles/year.

Fractal study of the mechanical properties of hardened hydraulic hammer parts

Abstract. Problem. Intensive abrasive wear of hydraulic hammer parts during operation leads to a decrease in their residual life. Since the existing methods of volumetric and surface strengthening of parts do not give a significant effect, the involvement of the ion-plasma chrome plating method has become relevant. Methodology. High-quality chrome coatings are obtained at a substrate temperature of at least 80–100°C. On the basis of experimental studies, the effect of ion-plasma chromium plating on the wear resistance and mechanical properties of hydraulic hammer parts was established, and structural changes in the material were also analyzed. The technology of ion-plasma chrome plating ensures the operation of hardened parts without chipping and crushing and increases their wear resistance by 1.75 times. Zones of structural transformations, characteristic of secondary hardening phenomena, are noted in the areas of damage to the parts. Results. Fractal theory, in particular, multifractal analysis using the Rényi equation, was used to analyze the non-homogeneous surface of hydraulic hammer parts (hammers, picks). The sorbitol structure of the bran and peaks was considered at ´ 100. Models describing the relationship between mechanical properties and multifractal characteristics of the structure were obtained: homogeneity of D600, orderliness (hidden periodicity D = D1-D600 , regularity K = D-600-D600. Adequacy of the models is confirmed by Durbin-Watson statistics at the level of 2.62 and 3.12. The sensitivity of the studied multifractal statistical characteristics of cementite to the strength properties sB (0.80) and s0.2 (0.96), as well as ferrite to plastic properties d (0.97) and y (0.97) was established. Practical value. The obtained results allow us to use this approach as an express method of non-destructive control when predicting the mechanical properties of the relevant parts of the hydraulic hammer after ion-plasma chrome plating.

Відновлення та зміцнення деталей і робочих органів сільськогосподарських машин, працюючих в абразивному середовищі

The working bodies of tillage agricultural machines (ploughshare, plow shelf, cultivator paw, harrow disc) work in conditions of abrasive operation, shock loads and the impact of external aggressive environment. Their repair is to restore the original size of parts and wear resistance of functional work surfaces. During the operation of tillage machines and units, the working surfaces are subjected to uneven wear, which reduces the life of parts and increases the cost of their replacement and restoration. The working bodies of tillage agricultural machines (ploughshare, plow shelf, cultivator paw, harrow disc) work in conditions of abrasive operation, shock loads and the impact of external aggressive environment. Their repair is to restore the original size of parts and wear resistance of functional work surfaces. During the operation of tillage machines and units, the working surfaces are subjected to uneven wear, which reduces the life of parts and increases the cost of their replacement and restoration. The current level of operation of agricultural machinery is characterized by increased speeds and high productivity, which, in turn, leads to increased wear of parts. accordingly, the reliability of the recovered ensure the restorative parts. Surfacing makes it possible to obtain layers of any thickness and chemical composition on the working surfaces of parts; apply a welded layer with different properties, ie high hardness and wear resistance. In this work we use point (point) hardening, which consists in micro-dripping of the hard alloy into the surface structure of parts that undergo intense abrasive wear. The geometry of the hardening point is a spherical sector, which facilitates the rapid removal of heat from the surfacing bath in the base metal and the environment, so the hardening points harden at high speed and in a short time. At point strengthening of details one of the main conditions providing stable quality of process - coordination of welding current and arc voltage. The sawtooth profile of the ploughshare blade (cultivator paws) is maintained throughout its service life. providing effective cutting even with the blades worked. We will fully consider the welding stress and deformation of the steel and tungsten carbide, to ensure the using performance of products. About tungsten carbide, we use the most advanced production equipment and the most reasonable production process during the material selection, burdening, pressing and sintering. We always fully consider the special requirements of different products on the strength, hardness, grain size of tungsten carbide.

EVALUATION OF NOMENCLATURE OF MACHINE PARTS, THAT DETERMINE RESOURCE

The development of machine designs occurs with a constant desire to increase their productivity, which is almost always accompanied by an increase in the mechanical and thermal tension of the movable joints of parts. At the same time, the tasks of achieving high reliability and durability of the machine, reducing its weight, reducing the consumption of scarce materials are set. Based on a comprehensive assessment of automotive parts that determine the resource, it was found that abrasive wear prevails over all other types of wear. About 83% of automotive parts have wear up to 0.6 mm. When interacting with the soil, the working bodies of tillage and planting machines are subjected to intense abrasive wear. In addition, the working bodies of agricultural machines are operated in a chemically abrasive environment, which is associated with the addition of various fertilizers to the soil and the presence of moisture in it. Together, these factors have such a strong influence on the working bodies of agricultural machines, which makes them unusable after almost several hours of intensive work. Currently, in Ukraine, the following working bodies of tillage machines are used for tillage in agriculture: ploughshares, pointed and one-sided cultivator paws, various coulter designs, harrow discs, husker discs, baking powder, etc. In the soil environment, the working bodies are subject to intense abrasive wear. Typical representatives of the working bodies of tillage machines with cutting elements are the paws of cultivators designed for loosening, destroying weeds and mixing soil particles. The analysis of methods and methods of restoration of machine parts used at the enterprises of the agro-industrial complex showed that more than 60% of the parts are restored by surfacing and gas thermal spraying. Keywords: resource, repair, restoration, surfacing, thermal spraying, wear, durability

Preliminary studies of increasing the durability of forging tools subjected to various variants of surface treatment used in the hot die forging process of producing valve forgings

The paper discusses the durability of forging punches used in the industrial precision forging process of prducing valve forgings for truck engines. The tools are made of 1.2365 steel, and the forging material is high chromium-nickel steel -NCF3015. Due to the hard operational conditions in the forging process (cyclic thermal loads and high mechanical stresses, intensive abrasive wear), the tool life, in the case of forming these steels, is much shorter than in the case of producing forgings from typical carbon steel. In order to increase the durability of the punches, a surface engineering hybrid layer type: GI (ion nitride surface) and four PVD coatings (CrN, TiAlN, AlTiCrN and AlTiCrSiN) were used on a punch, whose working surface was divided into 4 quarters (one coating by one quarter). The tool wear was analysed and represented by the material destruction on the working surface of the punches, based on the 3D scanning and the change of the material volume of the periodically collected forgings (Indirect 3D scanning method). The punches were also subjected to a surface analysis with the use of SEM as well as a microstructure analysis (Light microscope) and hardness measurements. Based on the preliminary analysis, it was established that a few various destructive mechanisms are dominant (coating chipping and adhesive wear). The best results were obtained for the TiAlN coating and the worst for AlTiCrN. In order to confirm the final results, it is necessary to carry out further tests (one coating for one working surface of the punch) under industrial conditions.

Wear phenomena in different cemented carbides during rotary-percussive drilling in reinforced concrete

Rotary-percussive drilling through steel reinforced concrete not only subjects cemented tungsten carbide drill bits to intensive abrasive wear but additionally induces significant microstructural changes in the near-surface regions. These include micro-, meso- and macroscopic cracking; comminution of the WC; delamination of WC-binder interfaces; binder depletion and pore formation; partial WC dissolution and rearrangement; surface decarburization; and the creation of secondary phases within the binder.In this study, the wear phenomena in cemented carbide drill bits with different WC grain sizes (fine to extra coarse), binder contents (6–12 wt%) and binder types (Co, CoNi and Ni) have been documented, analysed and quantified. Noticeable differences between the various grades are evident.A wide range of experimental variables have been investigated covering the large proportion of real-world cases encountered in the application of these drill bits on the construction site. This paper presents a broad overview highlighting how material choice influences wear.

Підвищення технічного ресурсу і довговічності робочих органів ґрунтообробних сільськогосподарських машин

The working bodies of tillage agricultural machines (ploughshare, plow shelf, cultivator paw, harrow disc) work in conditions of abrasive operation, shock loads and the impact of external aggressive environment. Their repair is to restore the original size of parts and wear resistance of functional work surfaces. During the operation of tillage machines and units, the working surfaces are subjected to uneven wear, which reduces the life of parts and increases the cost of their replacement and restoration. The working bodies of tillage agricultural machines (ploughshare, plow shelf, cultivator paw, harrow disc) work in conditions of abrasive operation, shock loads and the impact of external aggressive environment. Their repair is to restore the original size of parts and wear resistance of functional work surfaces. During the operation of tillage machines and units, the working surfaces are subjected to uneven wear, which reduces the life of parts and increases the cost of their replacement and restoration. The current level of operation of agricultural machinery is characterized by increased speeds and high productivity, which, in turn, leads to increased wear of parts. accordingly, the reliability of the recovered machines will depend on the wear resistance and fatigue strength of the recovered parts. The leading place in the repair of machines is occupied by welding and surfacing processes, which account for about 80% of all restorative parts. Surfacing makes it possible to obtain layers of any thickness and chemical composition on the working surfaces of parts; apply a welded layer with different properties, ie high hardness and wear resistance. In this work we use point (point) hardening, which consists in micro-dripping of the hard alloy into the surface structure of parts that undergo intense abrasive wear. The geometry of the hardening point is a spherical sector, which facilitates the rapid removal of heat from the surfacing bath in the base metal and the environment, so the hardening points harden at high speed and in a short time. At point strengthening of details one of the main conditions providing stable quality of process - coordination of welding current and arc voltage. The sawtooth profile of the ploughshare blade (cultivator paws) is maintained throughout its service life. providing effective cutting even with the blades worked.

Tribological Behavior and Microstructural Analysis of Atmospheric Plasma Spray Deposited Thin Coatings on Cardan Cross Spindles.

Cardan joints are used in transmissions between misaligned shafts, as in all-wheel-drive (AWD) cars and railway applications. Their functioning is accompanied by heavy cyclical loads, with the cardan cross spindles subjected to intensive abrasive wear and pitting. In this paper, a solution to the mentioned issue is proposed, thin anti-wear coatings of Metco 32 and Metco 72 metallic powders deposited by atmospheric plasma spray (APS) on cylindrical samples cut from spindles of two cardan crosses made of 40Cr10 and RUL2 steel. The morphological analysis of the coated surfaces was realized by scanning electron microscopy (SEM), and the elemental composition of the tested samples was elaborated by energy-dispersive X-ray spectroscopy (EDS). To investigate the wear resistance of the coated samples in dry and grease-lubricated conditions, tests at constant load and constant speed were carried out using an AMSLER tribometer. The results of greased tests proved that the expulsion of the lubricant from the tribological contact occurred no matter the combination of coated or uncoated samples. During grease-lubricated tests of ten minutes, the least coefficient of friction was measured for uncoated specimens with better surface finishing; but in dry friction tests, the lowest values of the mean friction coefficients were obtained for the Metco 72 coatings. The porous coatings may act as lubricant reservoirs in long-lasting tests, providing a solution to the expulsion phenomenon of the lubricant to the boundary outside the area of the larger-diameter roller.

Wear Analysis of Forging Tools Used in an Industrial Production Process—Hot Forging in Closed Dies of the “Head-Disk” of an Engine Valve Forging

The article performs an analysis of the durability of punches applied in the process of producing a valve forging from chromium-nickel steel. A forging of this type is made in two operations: coextrusion of a long shank, followed by finishing forging in closed dies of the valve head. The product obtained in this way (after other additional finishing procedures) constitutes the key element of the combustion engine (resistant to high pressures and temperatures) in motor trucks. Unfortunately, a significant problem in this production process is a relatively low durability of the forging tools, especially the punch used in the second forging operation. The key element at this stage, deciding about the punch’s further operation, is the area of the so-called “calotte”. The short-term life of the tools results from very hard performance conditions present during the forging process (periodical high mechanical and thermal loads, long path of friction). The latter cause intensive abrasive wear as well as high adhesion of the forging material to the tool surface. Based on the performed studies, including the following: technology analysis, numerical modelling, macro analyses combined with 3D scanning of tool sections as well as microstructural tests and hardness measurements, it was established that it is crucial to properly select the process parameters (charge and tool temperature, tribological conditions), as even slight changes introduced into them significantly affect the operation time of the forging tools. Mastering and proper implementation of the analyzed forging technology requires numerous further studies and tests, which will enable its perfection and thus increase the durability of the tools as well as the quality of the produced items.

Preliminary Failure Frequency Analysis of Receiving Bins in Retention Bunkers Operated in Underground Copper Ore Mines

Ore retention bunkers and receiving bins are important for continuous operation of transport system in a mine. Although the designs of the bins used in the KGHM PM S.A. mines have undergone modifications, their operating principle has remained unchanged since their initial commissioning. Their operation entails many problems, which are caused by the durability and functionality of the entire structure. Preventive actions and research into directions for possible modernizations require the type of damage and its reasons to be identified in the first place. This article presents an evaluation of the documented types of damage and an analysis of the repair works performed for the entire population of the receiving bins operated in one mine. The comparative evaluation of the bin failure rate is here proposed to be performed with the use of a number-based failure indicator and of a mass indicator. The key problem identified in the research was the wear and tear on steel elements due to abrasive processes. The linings of the bin elements were observed to undergo intensive abrasive wear. This abrasive wear of the analyzed bin elements is influenced by a combination of factors, the most important of which include variable physical and mechanical properties of the copper ore.

Preliminary Studies of the Durability of Tools Used to Form Ceramic Tiles Made of Hardox 600 and NC11LV Steel

The study performs a comparative analysis of the wear of tools made of two wear-resistant materials: steel Hardox 600 and NC11LV, used in the process of forming a band for roofing tiles. The analyses were to allow the assessment of the possibility of replacing the standard material for tools in this process with a much less expensive tool steel for cold work after heat treatment (with a large number of carbides), as an alternative material dedicated to tools resistant to intense abrasive wear. The performed investigations included a macroscopic and geometrical analysis with the use of 3D scanning, microstructural analyses conducted by means of a light microscope, as well as an analysis of the topography of the working areas of the tools with the use of SEM, and microhardness tests. The obtained results demonstrate that the tools made of both materials were characterized with a similar level of wear, which, in the most critical area, reached over 4 mm, while the tools made of steel NC11LV worked over a much longer period of time without regeneration, equaling 912 h, and an insert made of steel Hardox 600 operated for 384 h. A higher tool life in the case of NC11LV steel may be the result of higher hardness and the presence of hard carbides.

Improving Hardness and Wear Resistance of Sparingly Alloyed High-Strength Steels for Production of Items Operating under Conditions of Intense Abrasive Wear

Improving Hardness and Wear Resistance of Sparingly Alloyed High-Strength Steels for Production of Items Operating under Conditions of Intense Abrasive Wear

Steel quality of rolling contact bearings produced by different manufacturers, used for mining equipment instrumentation

Severe operating conditions of mining equipment have a negative impact on the operating life of the rolling contact bearings used in such equipment. The main reasons for the premature failure of rolling contact bearings include, first of all, poor quality of the bearing steel as delivered and the defects of their subsequent heat treatment. The abovementioned reasons result in splitting of bearings, metal shelling and appearance of potholes on their tracks, as well as intense abrasive wear. Nevertheless, despite the importance of this issue, the quality of bearing steel, either as delivered or in finished bearings, is usually not under control.To solve this problem, the quality of bearing steel was studied, exemplified by the bearings of the Russian, Swedish (SKF) and Japanese (NSK) manufacturers, i.e., main suppliers of rolling contact bearings for mining equipment in Russia. The problem of bearing steel quality control was solved by developing a quality control methodology that took into account the state of the metal after metallurgical treatment and at the stage of bearing production. Based on this methodology, the main types of bearing steel defects affecting the mechanism of bearing failure are identified.It is found that the bearing steel quality of domestic manufacturers is highly competitive with foreign counterparts. A method of nondestructive control is also proposed for detecting possible microstructure defects in bearings, either as delivered or while in operation.

The height of the pumping unit suction pipe inlet relative to the riverbed bottom

Currently, 78% of all irrigated land in Uzbekistan is provided with water by pumping stations and installations. The water sources of most pumping stations are rivers and irrigation channels that transport a large amount of bottom and suspended sediments. Due to the lack of consideration of bottom sediments moving in the form of ridges, when installing the pumping units suction pipeline, during their operation, these bottom pumps flow from the water intake source in the interior of the units. As a result, intensive waterjet wear of the flow part and the impeller of the pumps occurs. This leads to an intensive reduction in the main parameters of the pumps, as well as reduces their repair period. Currently, this is one of the major problems of pumping stations that take water from the Zarafshan river, as well as those operating on the Karshi, Amu-Bukhara, Amu-Zang and Jizzakh main channels. Laboratory studies were carried out on the experimental installation to determine the height of ridges with different granulometric composition of bottom sediments. As a result, a formula was obtained for determining the height of the ridge, taking into account the heterogeneity of ridge forms. Based on the obtained formula, a method for setting the height of the pumping unit suction pipe inlet relative to the riverbed bottom is recommended. The application of the proposed method does not allow bottom sediments to enter the inner part of the pumps, as a result of which their intensive abrasive wear decreases, the inter-repair period increases, while maintaining its main parameters for a long time.

Использование шеелитового концентрата для повышения износостойкости рабочей поверхности, восстановленной при электрошлаковой наплавке

Parts subject to intense abrasive wear have a short service life. In the manufacture or restoration of such parts by electroslag surfacing, strengthening of the deposited metal is required. The use of ready-made alloying powders in surfacing increases the cost of the finished part, which necessitates the search for cheaper materials for alloying the parts being welded. The study of the efficiency of alloying the deposited metal through the melted insert, as well as by direct introduction of alloying powders into the slag bath has been carried out. Mixtures based on enriched mineral scheelite concentrate and graphite are used as alloying powders

Hardfacing of Copper

The article discusses the primary issues of the hardfacing of copper elements exposed to intense abrasive wear, gas-abrasive wear at high temperature and in contact with liquid metal. In addition, the article presents test results concerning the surfacing of copper grade M1 performed using a self-shielded flux-cored wire providing weld deposit Fe14 and plasma powder surfacing performed using powder providing weld deposit Ni3 (in accordance with EN 14700).

Improving the durability of moving joints working in conditions of intensive wear

The article discusses the method of surface plastic deformation of steel parts by rolling them with rollers. The positive effect of this method on the wear resistance of friction pairs under conditions of intense abrasive wear and with abundant lubrication has been established.

Improvement of Abrasion Resistance of Production Equipment Wear Parts by Hardfacing with Flux-Cored Wires Containing Boron Carbide/Metal Powder Reaction Mixtures

Abstract In this work was established that serial traditional hardfacing materials based on the Fe-Cr-C system are not effective for improvement of abrasion resistance of elements of equipment for production of bricks, solid fuel briquettes and for restoration of augers, due to the fact that this equipment works at significant specific and cyclic loads. Features of the coarse-grained structure of Fe-Cr-C based coatings leads to intensive abrasive wear. The aim of this study was to increase a durability of that equipment by using of flux cored electrodes with reaction components of Ti, Cr, Mo, B4C and their combinations to provide synthesis, which leads to fine-grained structure of refractory borides and carbides and their solid solutions with increased hardness. Structure of the hardfacing coatings were investigated by method of metallography, scanning electron microscopy (SEM), electron backscatter diffraction (BSD) mode and energy dispersive X-ray spectroscopy (EDS). Temperature dependences of equilibrium phase amount of the hardfacing materials were calculated by the CALPHAD technique, using JMatPro software. It was investigated that the offered materials are characterized by higher wear resistance at high specific and cyclic loads in comparison with serial production high-chromium hardfacing materials (Lastek, ESAB, Paton IEW). It was established that the abrasion wear resistance at high specific and cyclic loads depends mostly of formation of the structure of hardfacing material, and not the hardness. Also, using of powders of pure metals and their combination as reaction mixture for FCAW leads to fine structure which contains of refractory borides and carbides and their solid solutions.