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The last decade has seen the use of powerful computerized Mine-Wide Monitoring (MWM) systems for detecting hazardous conditions in underground coal mines. Recently, the U.S. Bureau of Mines and Jim Walter Resources, Inc. (JWR) expanded the scope of MWM system to include ground control. Single-point extensometers were installed in each of 30 intersections along a tailgate entry. These instruments monitored the rate of roof sag, a sensitive indicator of roof instability. Data were collected by the mine's own computerized MWM system. The paper describes the successful integration of ground control instruments into MWM, the data reduction procedures, and the identification of several hazardous areas.

Jan 1, 1994

By D. R. Irving

Prior to this time, ample supplies of high grade mineral fillers, such as clay, have been available close to consuming centers. Now depletion of these accessible deposits, coupled with other factors such as increasing demand due to population expansion and standard of living rise, has made development of upgrading techniques attractive to producers. Various investigations being carried out by the U.S. Bureau of Mines are described. Factors making the development of improved methods for upgrading clays attractive to producers include: depletion of accessible deposits of high-grade clays, rising transportation and labor costs, more exacting specifications, and increased demand resulting from an expanding population and a constantly rising standard of living. Industry recognizes the need for upgrading presently unusable materials and has cooperated with the U.S. Bureau of Mines by providing samples from submarginal deposits and by evaluating the products that USBM upgrades. Following are some examples of recent clay beneficiation work by the Bureau. FIRE CLAY BENEFICIATION At the Rolla Metallurgical Center, Rolla, Mo., the Bureau is conducting research to develop technically and economically feasible mineral-dressing methods to remove quartz, pyrite, and other impurities from submarginal fire clays. The research has been spurred by the growing shortage of high-grade bur-ley, flint, and plastic clays in the Missouri fire-clay district resulting from increased consumption and the low rate of discovery of new deposits of adequate quality. There apparently is ample tonnage of submarginal flint and plastic clays to maintain the industry for many years if such material can be upgraded to commercial quality. Samples have been submitted to USBM by several major producers of refractories, including A. P. Green Fire Brick Co.; Harbison-Walker Refractories Co.; Mexico Refractories Div., Kaiser Aluminum and Chemical Corp.; and Wellsville Fire Brick Co. Research on some samples has been completed and still is in progress on others. The Bureau has found that specimens containing quartz or pyrite in grains coarser than the accompanying clay generally can be upgraded either with a gravity table or hydraulic cyclone. The improvement in quality is notable not only in chemical analysis but in an increase in pyrometric cone equivalent (PCE) of one or more cones. As an example, consider the results attained on a sandy flint—a fine-grained mixture of kaolin and halloysite with quartz and minor quantities of iron and manganese oxides. Chemical analysis was: 35.4 pct alumina (A12O3) and 47.8 pct silica (SiO2). The sample contained 9.2 pct free silica as quartz. The PCE was 33. The sample was crushed to -10-mesh, blunged with water, and then stage-ground to -48-mesh. The ground sample was tabled to yield a clay fraction containing 37.6 pct A12O3, and 45.3 pct SiO2 of which 2.4 pct was free silica. The PCE was 34. Recovery of alumina by this process was 73.6 pct. Concentration of the same clay in the hydraulic cyclone was even more effective in respect to quartz removal. The clay fraction analyzed 38.6 pct A12O3, 45.0 pct SiO2 of which 0.5 pct was free silica as quartz, and had a PCE of 34. Recovery of alumina was 71.9 pct. The hydraulic cyclone was also effective in reducing the pyrite content of a plastic clay which likewise was a mixture of kaolin and halloysite, plus some pyrite, quartz, and carbonaceous material. It analyzed 30.6 pct Al2O3, 52.3 pct SiO2, 2.3 pct Fe2O3, and 0.76 pct S. The sample was blunged and screened through 10-mesh to remove some coarse pyrite, then ground to -65-mesh and cycloned to remove most of the remainder. The final product recovered 81.8 pct of the alumina at a grade of 32.3 pct A12O3, 50.9 pct SiO2, 1.4 pct Fe2O3, and 0.1 pct S. The PCE was 32-1/2, compared with a PCE of 31-1/2 for the crude clay. The fine beneficiated clays, of course, must be pelletized and dried or fired to meet commercial acceptance. This operation has already been solved by industry. Little progress has been made on two remaining problems. One is that of fine-grained impurities, not separable by table or cyclone. Flotation is being investigated to solve this. Although fine pyrite is readily rejected, a satisfactory quartz-clay separation has not been attained. The second problem, a stubborn one, is that of alkali. Samples containing as much as 5 pct potas-

Jan 1, 1961

By Nick Vayenas, Ming Cai, Hongbin Zhang Lorrie Fava, Enrique Acuña

"A hybrid methodology is proposed to improve the accuracy of Diesel Particulate Matter (DPM) concentrations simulated in a ventilation network model by using Computational Fluid Dynamics (CFD). DPM, as a primary concern for underground hard-rock mines, has been studied in two dominant numerical models, ventilation network solvers and computational fluid dynamics. Ventilation network solvers are efficient, but they are not able to provide three-dimensional DPM concentration contours and only accept area-average DPM data as input. CFD simulations are time-consuming, but generating DPM concentration results with high accuracy. Besides, both monitoring points and planes can be created in a CFD model, which can take both point data and area-average DPM data as input. The hybrid methodology is intended to combine the advantages of the two by using the CFD results to update the network model results at key locations. A field study was conducted in a dead-end heading in an underground gold mine in the United States. Real-time DPM monitors were used to collect data. A CFD model and a network model were built for the experiment area. The CFD model was calibrated to the experimental data. In the study presented here, results from a calibrated CFD model are converted to equivalent diesel emission rates in the ventilation network model at a shared outlet. The hybrid methodology is used to provide better input for the network model. INTRODUCTION Mine ventilation system is one of the most important parts for an underground mine. It not only provides fresh air to the personnel but also helps clear the contaminants generated from the diesel-powered equipment. For most underground metal and non-metal mines, diesel particulate matter is the main contaminant. It is also the focus of this paper."

Jan 1, 2019

By Brian P. Canning

Ion exchange resin processes are receiving renewed attention in the mining industry for recovery;, of metals from solution. This interest has been inspired by the development of continuous countercurrent ion; exchange systems (CCIX) which are of much lower cost than the original, fixed bed contactor processes. With the countercurrent systems and new developments to process or upgrade the eluate product, ion exchange can now compete successfully with solvent extraction for treatment of uranium ores. The low concentration of U308 obtained in the CCIX strong eluate is generally upgraded by solvent extraction methods in sulfuric acid systems. Resin loadings of up to 120 grams per liter of U308, however, have been produced experimentally by recycling of eluate (HIM-IX process) and further developments may be expected in the near future. New developments in resin technology are bringing forth products of greater strength, loading capacity, selectivity and density. Densities up, to 1.35 spgr have been claimed by some suppliers. The process is not a new one and has taken years to advance to the present state of development. The earliest system to gain widespread acceptance was the resin-in-pulp system applied to uranium recovery. Ion exchange, however, later lost acceptance in favor of solvent extraction in the 1960's due to problems in resin degradation, resin contamination and resin-pulp separation, in addition to the development of improved solvent extraction reagents and techniques. The resin-in-pulp system continues to have application on high clay ores and has advanced in design. A number of other continuous ion exchange systems were also tried but never gained continued acceptance. In the current resurgence period the CCIX systems to gain acceptance were the Utah and Chem-Sep (Higgins Loop) systems. These processes are relatively simple in concept although require sophisticated controls. Fixed bed columns have also been designed into multistage systems in countercurrent operation but are not discussed in this paper. These systems remain competitive today for many applications. The most recent advancements however have been in the multistage contactors from,, which three are in current acceptance. These are the Himsley, Porter, and NIM systems. All industrial applications of these systems are relatively new, although pilot plant and in-plant development has been in progress over the last decade. Fur36ther developments should be expected in the near future.

Jan 1, 1979

"Discrete Fracture Network (DFN) modelling has increasingly being used in many geotechnical and mining engineering problems, the authors believe there is an ever greater demand to provide updated guidelines that address the collection of discontinuity data in the specific context of DFN models. In general terms, the generation of a DFN model requires collecting information on i) fracture orientation, ii) fracture intensity, iii) fracture length and iv) fracture terminations. The International Society of Rock Mechanics (ISRM) suggested methods for the quantitative description of discontinuities in rock masses directly include most of these parameters. However, there are important differences engineers should be aware. To what extent discontinuities can be sampled and which limitations are inherently introduced in the analysis by the sampling methods being adopted represent important aspects that should drive the collection of discontinuity data for DFN analysis; this will require the introduction of a more appropriate set of guidelines bridging the gap between the current, very practical, ISRM methods and the data requirements imposed by the use of new DFN technologies.INTRODUCTIONThe last decade has seen a major increase in use of the Discrete Fracture Network (DFN) approach, both as a stand-alone tool or integrated within more complex geomechanical simulations (Rogers et al., 2014 and Elmo et al., 2014). In particular, the DFN approach offers the opportunity to maximise the use of fracture data collected from mapping of rock exposures and to construct synthetic rock mass (SRM) models. However, the potential of DFN based modelling is limited if there is insufficient care in collecting the necessary structural data at the required engineering scale. DFN models are also subject to the process of data calibration and validation (Hadjigeorgiou, 2012). With DFN modelling becoming an almost integral part of many geotechnical and mining engineering problems, the authors believe there is an ever greater demand to review the process of collecting fracture data in the specific context of DFN modelling.The value of the DFN model depends directly on the quality and quantity of available field data. For example, fracture length (persistence) is an important parameter in DFN modelling; however, this parameter is either seldom available at the pre-feasibility stage due to a lack of exposures (man-made or natural), or engineers have access to limited length data collected along exploratory drifts. Characterisation of rock exposures should also take into account limits of window/scanline mapping techniques with respect to both trace length bias and the effect of cut-off assumptions inherent in the mapping methodology."

Jan 1, 2015

This paper describes developments in ferro-nickel furnace technology, specifically improvements to cooling methods, furnace controls, and high voltage furnace operating regime. The evolution of these technologies is briefly presented, as context for describing the current state of the art that has enabled ferro-nickel furnace operation at over 75 MW and specific energy consumption of less than 400 kWh/t dry ore. Examples from existing operations are used to illustrate present best practices, and potential future trends are discussed: The paper begins with an overview of the fundamental aspects of pyrometallurgical treatment of lateritic ores that drive ferro-nickel furnace design. Furnace wall cooling methods are related to the requirements resulting from specific furnace process conditions, including slag and metal compositions, as well as arc and bath power. The benefits of high productivity and low specific energy consumption resulting from high voltage (shielded-arc) operating practice are discussed, along with the furnace controls and electrical power train that enable such operation even with captive power generation. This paper is an update of that which the authors prepared for the Infacon X ferro-alloys conference.

Jan 1, 2004

By Scott Turner

GOLD AND SILVER, the monetary metals, have presented in the last year a striking contrast; gold has experienced unusual prosperity, while silver has been depressed more severely than ever before. Gold mining has been hailed as the only basic industry that is able to thrive on depression; the new gold produced is thought by many to be the most important material for the reconstruction of prosperity. Silver production, meanwhile, has been sinking to its level of 40 years ago, and its price to a level never before recorded. These factors have reduced the value of silver produced in 1932 to about the value of the average annual production more than a century ago, that of the decade 1801-1810. No other major commodity in world trade appears to have suffered a greater decline during the present depression.

Jan 1, 1933

By Egbert Burchardt

The challenge of "ore bodies getting steadily harder and lower in grade" was brought to light during the first oil crisis in the 70's. Shortly afterwards, HPGRs appeared on the scene with the promise of saving energy. This combined with developments in wear protection for the rolls ushered in a period of trade-off studies that considered the HPGR as an option to improve project economics or to even make projects feasible at all. Since then, applications of HPGRs at Cerro Verde (Freeport), PTFI Grasberg (Freeport), Mogalakwena (Anglo Platinum), Tarkwa (Goldfields), Boddington (Newmont), Penasquito (Goldcorp), and others have contributed to the creation of a formidable basket of operating experience. Collected through years of successful operation, this information has been used to validate design criteria, scale-up factors and establishing a clearer picture of what "to do" and what "not to do". This paper compares results from various mining operations using HPGRs in their processing plants. Some of the lessons learnt in different operating environments are reviewed in order to support proper implementation and operation of HPGR's. Some of the development programs that have been initiated to improve wear life of the tyres and to reduce overall operating costs are reviewed. It is timely to summarize today?s experience and analyse its implications for existing and new operations.

Jan 1, 2012

By S Serp, M Duchateau, P Chevreux

Molten salt reactor (MSR) is a promising advanced reactor system aiming to the transmutation of minor actinides such as americium in order to reduce the inventory of ultimate nuclear waste. The fuel is a molten salt in which actinides are homogeneously dissolved in the liquid phase. A chloride salt may be retained for this concept, as it provides low melting point, high solubility of actinides, harder neutron spectrum. To avoid corrosion and precipitation issues, molten salt composition has to be carefully controlled with impurity content as low as possible. Obtaining pure actinide chlorides without contaminants such as oxide, oxychloride, hydroxide and water is still a challenge. To prepare actinide-bearing salt, the chlorination of actinides oxides was investigated in an unstirred reactor under flowing gas as solid-gas reaction. The carbochlorination of PuO2 were performed in the temperature range of 600 to 800°C with chlorine gas as a chlorinating agent and the presence of solid carbon. PuCl3 was successfully synthesised by this method and characterised by X-ray diffraction measurements but some impurities such as oxide phase remain inside the formed product. Refinements of anhydrous and hydrated PuCl3 phases by Le Bail method were also performed for crystalline materials definition. Conversion mainly depends on the chlorinating temperature and the contact between the oxide and the chlorinating agent. A conversion value of 70–80 per cent was achieved at 700°C from PuO2 with quite high specific surface area. The conversion rate was not improved with increasing the chlorination time. The volatilisation of Pu was observed during the carbochlorination experiments. To avoid a loss of Pu caused by sublimation, the chlorination temperature should be limited to 650°C despite that the conversion of PuO2 to PuCl3 was enhanced by increasing temperature. Both carbochlorination and hydrochlorination of AmO2 were also carried out leading to the formation of AmCl3. These first results suggest that americium oxide was chlorinated more readily than plutonium oxide. The purity of produced PuCl3 and AmCl3 still deserves further investigations.

Jun 19, 2024

By Frank T. Duda

A U.S. Bureau of Mines interactive FORTRAN computer program can screen explosion-proof enclosures intended for underground service. The program incorporates important information and criteria to assist enclosure manufacturers and Mine Safety and Health Administration (MSHA) personnel by providing a first-order approximation of rectangular explosion-proof enclosure characteristics prior to actual certification testing. The program uses information and data that can be retrieved automatically during program execution. The program also performs the calculations for a series solution algorithm and various equations to evaluate the enclosure for both a static internal pressure and an internal explosion. The program writes the intermediate and final calculations and information concerning the status of the screening process to a summary file on a floppy disk. One data base contains MSHA certification requirements given in the Code of Federal Regulations (30 CFR 18). A second data base contains material properties of acceptable construction materials and weld joint efficiencies. A series algorithm determines bolt and cover stresses for a simply supported rectangular cover with arbitrary bolt locations. Limit and yield line analysis is used to calculate the strength of body panels.

Jan 1, 1989

By Javier Illanes, Maurice Moore, Felipe Moroni, Rafael Acosta

Any organization that subjects its activities to a continuous improvement process must be able to adequately measure the results of the implemented changes in order to pursue better results over time. This is no different for mining companies. When it comes to blasting, an accurate fragmentation analysis can correlate blast design and rock mass parameters to particle size distribution, enabling us to further analyze the correspondence of specific design patterns, applied to specific rock mass properties and the result in measured fragmentation indicators, such as P80 and fines percentage.

Sep 30, 2022

By M. Bergerman

Sossego was the first Vale SAG mill operation to process copper-gold ore. It is located in Para state, south east of Amazon region in Brazil. The comminution circuit was designed to treat 41 000 metric tons per day comprising primary crushing, one 11.6 m SAG mill operating in closed configuration with cone crushers, followed by two 6.7 ball mills. In the first three years of continuous operation Vale investigated alternatives for obtained improved performance of the circuit by investigating operating conditions, mainly focusing on SAG mill. A number of actions were then implemented, which resulted in significant increase in overall production. Vale then decided to further assess the performance of the comminution circuit as a function of ore characteristics. A comprehensive ore characterization program was then conducted, together with the calibration of mathematical models on the basis of surveys carried out at the industrial circuit. The simulator was then used to predict the production level associated to each ore type, as well as to establish the optimized circuit configuration and tailored operating conditions. The ongoing validation program is planned to consolidate the selected strategy, as well as showing the benefits in adopting such indices in mine planning, as opposed to rather simplistic approaches. This paper describes in detail the main aspects of optimizing the industrial circuit performance, as well as the successful method for predicting the production as a function of ore characteristics.

Jan 1, 2014

By Paul W. Johnson, Ralph C. Kirby, Frank A. Peters

An evaluation is presented for a process designed , on the basis of published work , to extract alumina as potassium alum from clay using sulfuric acid and potassium sulfate . The silica residue is separated by filtration . Ferric iron is reduced to ferrous iron , and the alum is crystallized from the solution , leaving the ferrous iron in solution . The alum crystals are separated from the solution and redissolved for feed to autoclave decomposition . In an autoclave the alum is partly decomposed to a basic alum , recovering five - ninths of the sulfuric acid and two - thirds of the potassium sulfate without using an acid plant . The basic alum is decomposed by calcining , and the potassium sulfate is then removed by washing with water . Operating costs for a plant producing 1,000 tons of alumina a day are estimated at $ 96.15 per ton of alumina . The fixed capital cost is estimated at $ 155 million . This process is not competitive under current economic conditions with the production of alumina from bauxite by the Bayer process . Improvement in leaching , basic alum decomposition , and washing could reduce the costs and improve the product which contains some potassium .

Jan 1, 1963

By Nicholas C. Williams

This paper presents the development of a demand reduction and responsive strategy capable of reducing the electrical power demand, particularly during peak conditions. The work presented includes a case study of a UK colliery. Areas explained are the equipment installation at the mine; the development of the demand reduction strategy including the load profile database and prediction optimisation model. Some live production data from the power meter installation at the mine is also presented.

Aug 1, 2013

By Ronald F. Ayers

The study upon which this paper is based was completed by Battelle's Columbus Laboratories for the U.S. Army Corps of Engineers in 1974. It is but part of an overall effort by the Corps to evaluate the costs and benefits to the nation of waterway improvements. This study is primarily concerned with future coal markets for production from those counties near the Wabash River in the heart of the Eastern Interior Province. An objective here is to consider a most pessimistic energy (and hence, coal) demand for planning purposes.

Jan 1, 1976

By A. J. Barry

This report presents observations made by Bureau engineers regarding hydraulic-powered roof supports that are currently being used or have been used on nearly all operating longwalls in the United States, A comparative summary of specifications for various types of powered supports with a brief description of the mine conditions has been compiled to enable mining engineers and mine operators to readily evaluate the differences in design data. Some of the support data furnished in the field may vary from those listed in manufacturers' brochures because of the trend to customize various support components to meet specific mine conditions. A method of estimating support requirements for different assumed operating conditions is presented. Similar computations for specific mine conditions may be used to make preliminary estimates of support requirements.

Jan 1, 1969

By J. K. Afidenyo

Microbial pretreatment of a double refractory gold ore was investigated using a white rot fungus, Coriolus versicolor (ATTC 20869) to improve gold extraction. A series of preliminary tests were conducted to determine the amenability of the ore to fungus degradation. Pulp density, temperature, pH and retention times were the process variables considered. Both a single. Stage and two-step processes were studied to establish process conditions. During the single stage process, the ore was contacted with the fungus culture (biotic) for 3weeks at 30°C and pH 10.0. For the two-step process, the first step involves ore contact with the culture medium (abiotic) at 45°C and pH 10.0 followed by fungal contact (biotic) at 30°C. Results indicated that carbonaceous matter is not degraded but passivated by the fungus; as preg-robbing activities dropped significantly from 18.1% to below 1.0%. The single stage process resulted in higher gold recovery than the two-step process Gold ex-traction by cyanidation of the pretreated ore was 78.9% for the single stage compared with 15.0% for the untreated ore. In the two-step process, only 73.3% gold extraction was achieved. Application of the two step process conditions to a high grade flotation concentrate, resulted in 93.3% gold ex-traction as against untreated concentrate of 30.5%. The results show that the microbial pretreatment process degraded sulfide sulfur, passivated carbonaceous matter and enhanced gold extraction from double refractory gold ore and concentrate.

Jan 1, 2014

By D Wimpenny

Underground infrastructure is often a critical component of transportation and utility schemes. It is characterised by long design lives with limited access for inspection and maintenance. The exposure environment can be difficult to assess since it will often vary substantially between different locations in the same facility and with time during construction and in service. In addition, the specific demands placed upon underground infrastructure are not well covered by the exposure classes and other guidance given within current codes of practice. When problems occur they can be difficult to rectify and involve significant disruption.Given these substantial risks the prudent designer may adopt a systematic ‘durability planning’ approach which:· defines the environment and principal deterioration mechanisms for the various elements and construction materials,· predicts the design life for alternative durability enhancement options, and· recommends associated measures to be adopted during construction and in service.This paper describes the development of durability planning within Halcrow, giving examples of its use from its first implementation on tunnels under the Suez Canal in 1993 to recent projects in the Middle East and Australia. It seeks to demystify the process, identify shortcomings and speculate on its future development within the civil and mining sectors.

Mar 8, 2011

By Andrew D. Lapworth

The use of geological and grade models has been standard practice in mine design for many years now, with a wide range of software available to create and analyze the models. Although geotechnical parameters are also of vital importance for mine planning, there has been very little in the way of commercially available systems for integrating geotechnical data into the mine planning and design process. Sirovision is a new technology based on digital photography for automated, safe and accurate 3D mapping of geological and geotechnical features in rock faces. Datamine has integrated this capability into its product range so that Sirovision becomes an integral part of day-to-day face mapping, mine geology and geological / geotechnical modeling in both open pit and underground mines. This results in improved fragmentation for loading, hauling and processing, and for open pits local geotechnical conditions can be taken into account to improve slope design and control. This paper describes some of the ways that geotechnical modeling can be used to create more refined and cost effective mine designs and then discusses the role of Sirovision in enabling the raw data required for such modeling to be collected quickly, safely and reliably.

May 1, 2007

By M. Dadvand, G. Kipuros, A. Dadvand

"The ability to codeposit fillers within a nickel matrix has led to the production of a new generation of cermet coatings with properties useful for various applications. Hexagonal boron nitride (hBN) is a ceramic-type particulate matter with thermal conductivity, thermal stability, inertness, and lubricity properties that allow it to be codeposited. In this paper, a method was developed for modifying hBN surfaces to allow them to be uniformly dispersed in water-based solutions such as an electroless nickel plating bath. hBN surface modification improved wear performance of the electroless plated cermet due to enhanced interaction between the particulate and nickel matrix. RÉSUMÉ La capacité à effectuer un dépôt simultané de charges dans une matrice nickel a abouti à la production d’une nouvelle génération de revêtements cermet (une combinaison de céramique et de métal) dotés de propriétés très utiles pour diverses applications. Le nitrure de bore hexagonal (h-BN) est une matière particulaire de type céramique utilisée pour ses excellentes conductivité et stabilité thermiques, son inertie ainsi que son caractère lubrifiant, qui permettent son dépôt simultané. Cet article explore une méthode mise au point pour modifier les surfaces du h-BN de manière à ce qu’elles se répandent uniformément dans des solutions aqueuses telles qu’un bain de dépôt autocatalytique de nickel. La modification des surfaces du h-BN a amélioré la résistance à l’usure du placage autocatalytique du cermet en raison d’une interaction accrue entre la matière particulaire et la matrice nickel.INTRODUCTION Electroless nickel alloy coatings can be used for many applications; however, the need for improved tribological properties such as higher wear resistance and better lubricity has increased interest in incorporating particulates (fillers) into the nickel matrix by codepositing the particulates with nickel during the plating process. The selection of the particulate type depends on the desired properties (Sahoo & Das, 2011; Sudagar, Lian, & Sha, 2013). In terms of tribological applications, electroless nickel-based composites are categorized mainly into lubricating and wear-resistant composite coatings depending on the type of particles incorporated. The electroless nickel-phosphorus (Ni-P) composite coatings are composed of codeposited solid lubricants such as polytetrafluoroethylene (PTFE), graphite, WS2, MoS2, and hexagonal boron nitride (hBN) and, compared to nanocomposite electroless Ni-P coatings, they demonstrate a lower coefficient of friction. On the other hand, the nickel-phosphorus wear-resistant composite coatings are composed of hard particles such as silicon carbide (SiC), aluminum oxide (Al2O3), boron carbide (B4C), silicon nitride (Si3N4), diamond, tungsten carbide (WC), and zirconium oxide (ZrO2) and, compared to nanocomposite electroless Ni-P coatings, they have higher hardness and better wear resistance (Sahoo & Das, 2011; Sudagar et al., 2013; Parucker, Klein, Binder, Ristow, & Binder, 2014; Chakarova, Georgieva, Petrova, Dobreva, & Stoychev, 2016)."

Jan 1, 2018