bluuebunny/crossref_metadata_2025 huggingface dataset:
Research of the gear changing process for a medium-tonnage cargo vehicle
Authors: Vashurin A S , Tumasov A V , Toropov E I , Trusov Yu P , Moshkov P S
Published: November 2019

One of the promising innovation vectors in the automotive industry is the automation of mechanical manual transmissions, which allows starting, maneuvering and changing gears in an automatic operation mode of the power unit, which ensures a reduction in the total time of the switching process, as well as enhances dynamic qualities and fuel economy of the vehicle. This article deals with the approach of scientists of Nizhny Novgorod State Technical University in the implementation of the project to automate the process of shifting gears of a GAZ medium-tonnage truck.
Ways of coordinating schedules in regional passenger traffic
Authors: Akifeva I , Voytenkov S , Banket M , Shapoval D
Published: November 2019

In the modern conditions of the Russian Federation in the traffic management field one of the priorities is the development and improvement of the route transport functioning quality. One of the main passengers’ requirements is the minimum travel time expenditures. Satisfying such a requirement without the mutual coordination of transport processes on routes and the use of roadside station by vehicles and passengers is problematic due to their interdependence. The problem of such coordination is inherited both in the cities, and in regional settlements. In this study, a methodology has been developed for coordinating bus schedules on regional routes that have common route sections or roadside station. This methodology was implemented in the Sargatsky district of the Omsk region. According to the obtained results, the average passenger waiting time in the case of a switch was reduced by 37%.
Analysis of the impact of the sample size on the accuracy of determining the travel time and buffer indices
Authors: Gorbunov R N , Gorbunova Z V , Kolchin V S , Yu Mikhailov A , Pirov Zh T
Published: November 2019

The article provides a description of such parameters for assessing the quality (efficiency) of the functioning of roads as travel time and buffer indices. A model describing the daily dynamics of travel time along a route, taking into account the possible presence of a traffic light object and an unregulated pedestrian crossing, is proposed. Using the model, the dependence of the accuracy of determining the temporal and buffer indices on the frequency of measurements is determined.
Analysis of using hydrogen in the internal combustion engines of motor vehicles to increase operational efficiency
Authors: Konoplev V N , Melnikov Z G , Korzin A S , Khripach N A
Published: November 2019

This paper examines the research and experiments on the use of hydrogen in transport to improve the energy efficiency of internal combustion engines (ICE) of motor vehicles (MV). Models of electrochemical hydrogen generator sets and modules with intermetallic compounds TiFeV onboard MV and technical measures for the correction of the engine control system algorithm are proposed.
Model of residual resource of automotive alternators
Authors: Puzakov A V
Published: November 2019

The urgency of the problem under study is caused by the imperfection of methods for diagnosing automotive alternators, which do not reveal hidden defects, as a result of which the alternator failure is sudden and entails costs due to vehicle downtime in repair. The aim of the study is a method for predicting the residual life of automotive alternators, built on the results of diagnosing and assessing the operating conditions of a car, for the first time considering the magnitude of the fluctuation of the output voltage. Analytical expressions describe the dependence of the intensity of an alternator resource on the ambient temperature and operating time, considering its technical condition at the time of diagnosis and the degree of its change under the influence of factors operating conditions on the test run. The theoretical results were confirmed by experimental measurements. The presented results can be used for the full implementation of the life of automotive alternators in the conditions of road transport enterprises.
GLONASS technologies as innovative development of road transport: social and economic impact
Authors: Grivanova O V , Grivanov R I , Reshetnikov R A
Published: November 2019

This article describes the current state of navigation technology within the motor transport sphere based on the GLONASS system. In this article, the example of the “ERAGLONASS” emergency alert system is used. Consideration is given to both the systems operation and technical solutions. Further consideration is also given to the experience of the implementation of the “ERA-GLONASS” system within the automotive industry. It also considers the impact of the state rules and regulation required to equip cars with this system on the market of used imported cars operating within Russia. The author further researches issues related to the organization of a system of authorized centers for the installation and maintenance for “ERA-GLONASS” equipment within the Primorsky Kray region and the associated social and economic consequences. Recommendations are made for further development of the application of technologies of global navigation systems in road transport, taking into account the positive and negative experiences of implementation to date.
Information technologies and management of transport systems development of the approach to assessing adaptation of the intersection transport model
Authors: Novikov A , Glagolev S , Novikov I , Shevtsova A
Published: November 2019

In the work the authors touch upon the main approaches to assessment of adequacy of modeling of the transport system. They study the main parameters which can be used during assessment of adequacy of a transport model. The object of the research is a process of movement of vehicles at controlled intersections. The subject of the research is the technique of assessment of adequacy of the transport model using certain parameters of traffic flow (intensity, delays, motion speed, queue length). During the research the authors have developed the algorithm of assessment of adequacy of a certain parameter modeling.
Planning of passenger transportation in the cities of Russia on the basis of sustainable development
Authors: Spirin I V , Yu Matantseva O , Grishaeva Yu M , Savosina M I
Published: November 2019

In cities, transport is the leader in the use of the sustainable development – SD concept. The article describes the features of SD of the urban transport in countries with a high level of economic development. In Russia SD of transport is carried out in accordance with national legislation. Urban transport plans should be developed in all regions and municipalities. The analysis shows that the development of transport plans should be preceded by the solution of a number of problems. The main problems are: the inability of administrations of territories and cities to solve new issues of transport planning; lack of methodological developments for designers of transport systems; a fragmentary information base of transport planning; lack of qualified developers of transport plans. The main ways of solving these problems are proposed. Attention is drawn to the need to take into account not only the internal results (they are received by investors and carriers), but also external results obtained by other persons. The formation of civil society institutions is a prerequisite for SD implementation. Training for environmentally and socially oriented professionals should be changed.
Fuel flow and pressure in common return line as a diagnostic parameter of electro-hydraulic injectors technical state
Authors: Yakimov I V , Krivtsov S N , Potapov A S , Svirbutovich O A
Published: November 2019

Electro-hydraulic injectors (EHI) are the most vulnerable components of the common rail injection system of a modern diesel engine. As a rule, the injectors’ diagnostics begins with the analysis of data of the automobile scanner. These data include the current of the high-pressure pumpmetering device, adjustment of fuel pulsewidth when balancing the engine cylinders. A comprehensive analysis carried out by means of a car scanner can be possible only if a pressure sensor is positioned in the control chamber of the injector of the common rail injection system. There are such systems, however the majority of cars, not equipped with them. The scanner data may be influenced by the technical state both of the engine and of the metering device. Consequently, it can be impossible to assess the technical state of the injectors only by means of the car scanner data. It is known that the technical state of the common rail injector is characterized by such indicator as individual fuel back drain.

There is a method of measuring the injectors’ individual leakages by back flow measuring, but it can be applied only if there is an access to individual drain nozzles of EHIs. In many existing common rail injection systems the injectors are located inside the engine, the access to them is hindered. Respectively, only the common return line access is available. High-quality diagnostics of injectors in such systems is possible only with the use of specialized testers, which inevitably leads to increased costs conditioned by disassembling and fitting. To reduce the time of diagnosing electro-hydraulic injectorssignificantly, a method of determining their individual backflow by the common return line was developed.
Theoretical research of impact of the changed elastic and damping parameters of vehicle tyres and loading on the wheels breakaway time from the cobblestone road
Authors: Pozdeev A V , Ryabov I M , Chernyshov K V , Erontaev V V , Novikov V V , Pokhlebin A V , Chumakov D A
Published: November 2019

The article is devoted to the theoretical research of impact of the changed tyre stiffness and damping on the wheels breakaway time from the cobblestone road when driving at different speeds. The spacial four-support five-mass mathematical model of GAZ 322132 two-axle vehicle dynamics has been developed considering the breakaway. There are the results of the mathematical model theoretical research in the form of dependences of the front left wheel breakaway time from different combinations of tyre stiffness and damping at different vehicle speeds.
Method of ensuring the active and operational safety of a motor vehicle with a science-based choice of a tire profile family with regard to the characteristics changes of shock absorbers
Authors: Ryabov I M , Pozdeev A V , Chernyshov K V , Danilov S V , Mukhuchev Sh M , Omarova Z K , Poluektov M V
Published: November 2019

This work contains a description and method of ensuring the active and operational safety of a motor vehicle with a science-based choice of the tire profile family with regard to the characteristics changes of shock absorbers. A specific example of the application of this method is given.
Formation analysis of soiling for side windows and the rear view mirrors of vehicle
Authors: Tsepov D S , Solomatin N S , Zotov A V , Rastorguev D A
Published: November 2019

The article provides a classification of soiling sources of side windows and rear view mirrors, taking into account different weather conditions. Criteria for assessing soiling degrees are presented. The analysis of soiling mechanisms from various sources is carried out. Visualization of the trajectories of liquid droplets in the air flow is presented. The processes of interaction of droplets with the car surface and the movement of fluid on given surfaces are considered. The main soiling sources of side windows and rear view mirrors have been identified. The results of modeling the precipitation of droplets on the front door glass are presented when analyzing the movement of flows overcoming obstacles in the form of two generations of rear-view mirrors. Two different designs LADA Kalina / Granta demonstrate a significant difference in their ability to prevent soiling.
The study on the factors influencing the quality of paint and varnish coating when repairing the car body
Authors: Khasanov I , Rassokha V , Kabanova O
Published: November 2019

Absract

The article presents the main results of the studies on the factors influencing the quality of paint and varnish coating of the car body while performing the emergency recovery repair. The relevance of scientific observations in the presented work is that the issues connected with the quality assessment of applying and drying of paint and varnish coating of the body are not studied to the full extent. It especially concerns the cars that need recovery repair after road accidents. The data presented in the article can be applied while assessing the technical state of the cars, injured as a result of break-down incidents; when training specialists in the automotive industry; with the color selection of paints and varnishes and further application on the body. The scientific work provides the contribution to the improvement of the efficiency indicators of the cars operation on the basis of defects testing of decorative protective coating of the body and the definition of the factors influencing the quality of paint and varnish coating during repair application. The scientific novelty of the article consists in obtaining the identification results of the most significant factors affecting the quality of the paint and varnish coating applied while repairing, aimed at the restoration of the critical state of the car body resulting from the traffic accident.
Effect of gasoline composition on the absorption and retention of fuel vapor by activated carbon of the automobile adsorber
Authors: Khodyakov A A , Khlopkov S V , Azanov A V , Kh Abu-Nidzhim R
Published: November 2019

The physicochemical characteristics of petrol samples are studied. It is established that the fuel purchased at fuel stations corresponds to the standard parameters presented in the EURO standard for unleaded petrol. The presence of saturated hydrocarbons in petrol is determined using concentrated sulfuric acid, which reacts with unsaturated (alkenes, olefins) and aromatic hydrocarbons, without reacting with saturated hydrocarbons. The fractional composition of petrol samples is determined from the distillation temperatures measured by a mercury thermometer included in the automatic oil distillation apparatus ARNS-1E, acidity titration with an alcohol solution of potassium hydroxide gasoline mixtures with 80% ethanol. An acid-base phenolphthalein indicator (pH = 8.0-9.6) is used to indicate an excess of OH−. The density of the fuel samples is measured with oleometers (densimeters), octane numbers (ON) - indicator (Octanometer) OKTAN-IM. The limit of the permissible absolute error of the measurement of ON is ± 2 octane units. It is established that all petrols without exception contain saturated, unsaturated and aromatic hydrocarbons. It is shown that of the seven samples studied, two samples have some peculiarities. It is concluded that when controlling the quality of fuel, it is necessary to take into account not only the conformity of the determined value to the parameter of the norm, but also the differences in the values of the indices obtained when testing a series of fuel samples.
The relationship between the housing cost and the transportation accessibility using the example of city Kemerovo
Authors: Shtotskaya A A , Kosolapov A V
Published: November 2019

The research on the influence of transportation and urban factors and transportation time, in particular, on housing cost was done in the article. The methods of statistic analysis (Statistica; MS Excel packs) were used. The transportation mobility of city residents was characterized using city Kemerovo as an example. The model describing the influence of resident incomes and transportation time on the housing cost was designed.
Technological bases of the improvement of agricultural transport-technological machines
Authors: Drovnikov A N , Yu Kalmykov B
Published: November 2019

Mechanical, electrical, hydraulic and pneumatic transmissions are used in transmissions of agricultural transport technology machines. Depending on the design tasks, the considered transmissions have different kinematic schemes, parameters and design solutions. At the same time, the number of possible options can be quite large; therefore, the determination of the preferred option is, as a rule, a multi-criteria task and often leads to a palliative or compromise choice. The main problem of their development is the adaptability of the design of the actuator to the requirements of the technological (working) process associated with the constant change in the state of the technological object. This paper presents the rationale for developing a theory of kinematic chains of positive orders (adaptive kinematic chains), creating a theory of the structure of adaptive kinematic and adaptive mechanisms in general, methods for static and dynamic analysis of adaptive mechanisms, as well as methods for calculating their basic parameters.
Research of surface quality of structural components made using additive technology of electric arc welding
Authors: Balanovsky A E , Osipov S A , Shmakov A K
Published: November 2019

A brief analysis of the existing methods of additive technologies with reference to the aviation industry is carried out. The prospects of this direction are shown taking into account the possibility of production of aircraft parts on the principle of “bottom-up”. The results of researches of additive technology of electric arc surfacing in carbon dioxide of complex parts are presented. In the course of the carried out studies technological peculiarities of the technology connected with the parameters of welding arc, melting of cladding wire have been found out. Arc current has the greatest influence on the appearance of the molding. The wire feed rate affects the height of the welded roll. It is shown that the stability of the welded rolls formation depends on the modes of metal transfer, which depend on the conditions of wire feeding and insertion into the melt bath.
Roughness of holes in metal and polymer composite bags
Authors: Chashhin N S , Pashkov A E , Ivanov Y N , Sturov A A
Published: November 2019

The article presents the results of the research on the influence of cutting modes on the parameters of surface roughness during finishing of holes in mixed packages containing composite and metal materials. The object of the study is a mixed package containing layers of polymer composite material (CFRP), as well as layers of titanium and aluminum alloys. The main technological equipment used in the study is an automatic drilling machine. Cutting tool -carbide six-toothed reamer. For carrying out of researches ranges of variation of modes of cutting have been chosen and the plan of experiment by means of software Statistica 6 is made. Two factors are considered under the plan of experiment: speed of cutting and delivery, the parameter of the allowance on expansion is introduced as the block factor. The models of multifactor dispersion analysis, which determine the influence of modes on the roughness of holes, were obtained empirically. Optimization of cutting modes has been carried out, the surface of desirability has been constructed, and recommendations on the choice of technological parameters of the process have been given.
Peculiarities of making bolt and rivet connections with interference when assembling the aircraft MS-21
Authors: Chernykh E V , Zaidès C A , Kudryavtsev A A
Published: November 2019

In this paper the peculiarities of installation of fasteners with tension during assembly of MS-21 aircraft are considered. In particular, we considered the aspects of the necessity of using bolt and rivet connections with tension during the assembly of the aircraft fuselage. We have developed a finite element model of the installation process with the rivet bolt in the hole of the package using the system of finite element analysis Simufact. We used the Elastoplastic Concept of Material Behaviour with Nonlinear Hardening Section. And obtained the characteristics of the stress-strain state of the bolt-ribbon joint elements at various moments of rod retraction, including at the predicted moment of shank tear off. It has been revealed that it is expedient to bring the retraction force up to the value close to destructive one. Determined the residual deformations after removal of axial load from the rod. It is proved that it is necessary to actualize the existing normative and technical documentation with specification of the value of the tool impact force on the rivet bolt rod.
Study of the microspructure of the alloy AMG3 after friction stir welding
Authors: Guseva E A , Konstantinova M V
Published: November 2019

The article contains data on the results of the study of the microstructure of samples of AMg3 alloy, which was subjected to melt and stir welding. For this purpose the methods of optical and electron microscopy, as well as the method of diffraction of backscattered electrons were used. It was found that there were four zones in the area of the welded seam, each of which had its own microstructure. The reasons of formation of this or that microstructure taking into account the influence of temperature difference and plastic deformation in the welding zone are explained.
Mathematical model to calculate key parameters of forming irregular lateral cuttings on sheet articles to eliminate such defects as “under-forging”
Authors: Mironenko V V , Larionova Y N
Published: November 2019

The paper considers irregular lateral cutting beyond OST 1.52468-80. It shows that standard methods do not provide solutions to forming of either element of a workpiece. The study suggests methods to find parameters of forming and technical characteristics of a part containing the given element. It also proposes method allowing eliminating such defects as “under-forging”. The results are compared with finite element analysis of forming and natural experiment. The paper makes the conclusion on the possibility of applying the suggested formulas.
Dynamics modeling of surface treatment with end spherical cylindrical milling cutters
Authors: Ponomarev B B , Gabanov E V , Nguen Sh Kh
Published: November 2019

The designs of modern vehicles and aviation can be traced to a constant increase in the range of parts that have complexly shaped free-form surfaces. Production of such quality parts requires new methods of automated mechanical engineering and particularly program operated multi-purpose five-coordinate machine processing. The paper is dedicated to dynamical modelling of surface treatment of materials by spherical cylindrical milling cutter. The simulation results are the basis for the formation of optimal conditions for machining free-form surfaces and determining combinations of tilt and advance angles and their optimization for positioning the tool for end milling of surfaces on five-axis CNC machines.
Vibration suppression methods at high performance drilling
Authors: Savilov A V , Pyatykh A S , Timofeev S A
Published: November 2019

This article discusses the possibility of suppressing vibrations when drilling holes with spiral drills. This article presents two methods of suppressing vibrations: modal analysis and modulation of cutting speed (changes in spindle speed - Spindle Speed Variation - SSV). There is a description of the considered methods with an indication of their advantages and disadvantages. The article also points out to experimental data that characterize the possibility of suppressing vibrations when drilling holes and a comparative analysis of various methods of suppressing vibrations when machining holes in samples of their structural steel. There is an assessment of the possibility of joint application of modal analysis methods and modulation of cutting speed during high-performance drilling.
Studying the dynamics of cutting process by a face mill cutter
Authors: Svinin V M , Nikulin D S
Published: November 2019

An overview of stepped end mills use for rough cutting of large allowances and finishing cut of flat surfaces is given, where they ensure a reduction in cutting forces, an increase in dynamic stability and performance rate. The study of oscillations in the direction of the longitudinal feed of the spindle and workpiece subsystems, as well as the spindle torsional subsystem, has been carried out by the simulation modeling method. Detailed pictures of the oscillations of these subsystems are obtained. Careful analysis of these oscillations using the basic principles of the regeneration theory of self-oscillations allows establishing their nature and mutual influence. It is established that the main reason for the increased dynamic stability of the stepped end mill as compared to the standard one is the reduction of the power load due to the group cutting scheme and an increase in the uniform distribution of the frequency spectrum of the cutting moment due to the variability of the actual angular pitch of the teeth. The revealed pattern serves as a methodological basis for the creation of progressive designs of stepped end mills. When developing them, it is necessary to look for new patterns of the relative position of the teeth when varying the difference in diameters of the stages and angular steps.
Comparative study of residual stresses when turning HSS-5 steel with varying feed
Authors: Tikhonov A G , Pashkov A E
Published: November 2019

The purpose of this article is a comparative analysis of the parameters of residual stresses in the steel HSS-5 after turning with a change in the longitudinal feed. The tasks posed in this study are: calculating the impact of the feed during turning on the parameters of residual stresses formed in the surface layer of the material; comparing the results of radically different methods for studying residual stresses. When conducting research, the method of XRD-analysis and the mechanical method for calculating residual stresses were used. The presented methods are most widely used in the determination of technological residual stresses in samples of various metals and alloys. These methods are widely used both under laboratory and in production conditions; they are characterized by satisfactory accuracy and convergence of results.
Relationship between tool tilt angle, shoulder plunge depth and process energy input for pin-less friction stir welded thin Ti-6Al-4V sheets
Authors: Gili A B , Hattingh D G , Bernard D
Published: November 2019

This paper reports on the initial process development towards evaluating pin-less friction stir welding as a feasible alternative joining technology for Ti-6Al-4V sheets. Initial research results were derived from “bead on plate” welds with a pin-less tool on 3 mm Ti-6Al-4V sheets to assist with decision making for joining 1 mm Ti-6Al-4V sheets. The study evaluates the shared influence of tool tilt angle and shoulder plunge depth on weld profile and process energy input for a pin-less tool. An experimental approach was followed, performing bead on plate welds with three tool tilt angles (0°, 1° and 2°) respectively at shoulder plunge depths from 0.15 mm to 0.25 mm in 0.05 mm increments. From critically evaluating the hardness profile and heat effected area below the tool shoulder, the shared influence of tool tilt angle and shoulder plunge depth could be analysed to give an indication of the best parameter combination for performing solid state welds on 1 mm Ti-6Al-4V sheet. Additionally, the thinning effect on the weld region was evaluated and compared to welds made with a pin. Future work will include quantifying surface residual stresses on the material and the relationship these stresses exhibits with the varying tool tilt and shoulder plunge depth. This work will assist in selecting weld parameter combination that will minimize tensile residual stresses in critical areas. Knowledge gained from this study forms the basis for the overall process development for joining 1 mm Ti-6Al-4V sheets by pin-less friction stir welding.
The effects of Ru, Cu, Zr and Hf on mechanical properties in Ti-Pt high temperature shape memory alloys
Authors: Mashamaite M P , Chauke H R , Ngoepe P E
Published: November 2019

Shape memory alloys (SMAs) have been widely used in the fields of actuators and aerospace industry due to their pseudo-elasticity and shape memory effect which are displayed in phase transformations. The martensitic transformations (MT) of TiPt is much higher, at approximately 1273 K and this is considered to be of potential technological interest for elevated temperature SMA applications. TiPt based alloys exhibit very low shape memory effect due to low critical stress for slip deformation compared to the stress required for martensitic transformation, hence it is necessary to enhance the mechanical properties of the equiatomic alloy. The first principles approach was employed to study the effect of the third element (M = Ru, Cu, Zr, and Hf) on the TiPt shape memory alloy. The supercell approach in VASP was used to substitute Pt with Ru and Cu, Ti with Zr and Hf on the TiPt structure to evaluate their mechanical stability from elastic properties for actuators and higher temperature applications. The Ti50Pt50-xRux and Ti50Pt50-xCux decreases in density with increase in Ru and Cu concentration, whilst the Ti50-xZrxPt50 and Ti50-xHfxPt50 substitution increases with an increase in their concentration, which result in larger lattice parameters. The heats of formation suggest that Ti50Pt50-xRux substitution is more thermodynamically stable than Ti50Pt50-xCux substitution, and Ti50-xHfxPt50 substitution is more stable than Ti50-xZrxPt50. The elastic properties suggest that the ternary structures become mechanically stable with an increase of the third element. The Ti50Pt50-xRux and Ti50Pt50-xCux substitution became more ductile with the increase in concentration. Zr and Hf substitution became more ductile at higher compositions (31.75 – 43.75 at.%). The Ru and Hf substitutions have potential to be used for high-temperature applications.
Effects of Mo content on the microstructural and mechanical properties of as-cast Ti-Mo alloys
Authors: Moshokoa N , Raganya L , Obadele B , Olubambi P , Machaka R
Published: November 2019

The effects of Mo content on the mechanical and microstructural properties of as-cast Ti-10Mo wt.% and Ti-15Mo wt.% alloys were measured in order to evaluate their possible use in biomedical applications. The microstructure and phase analysis of as-cast specimens were studied using an optical microscopy and X-ray diffraction (XRD). The micro-Vickers hardness properties of the alloys were examined using Vickers equipment and the elastic modulus was determined using the tensile test. Results indicated that the Mo content influenced the structure-property relationship. The relative density increased significantly with the addition of Mo, the optical microscopy results showed that CP Ti was characterised with an α’-phase lamellar structure and with the addition of Mo, the microstructure composed of β phase with equiaxed grains of different sizes with sub-grain boundaries were observed. The measured XRD patterns showed that the CP Ti consisted of α’-phase and with the addition of Mo, the resultant alloys consisted of the β-phase. The micro-Vickers hardness and elastic modulus increased significantly after the addition of 10 wt.% Mo and then decreased significantly when the Mo content was raised to15 wt.%.
Investigation of graphene-based nanocomposite for hydrogen storage
Authors: Baloyi S J , Ngqalakwezi A , Nkazi D , Ntho T A
Published: November 2019

In this study, a simple, fast, and green one-pot method was developed for the preparation of Ni/Graphene nanocomposite for the storage of hydrogen. The precursor graphene oxide was prepared from expanded graphite flakes using a modified Hummer’s method. Graphene oxide was reduced effectively using natural reducing agents such as lemon juice as eco-friendly potential reducing agents instead of harmful hydrazine (N2H4). The characterization of as-synthesized graphene oxide and Ni/graphene nanocomposites were performed by powder X-ray diffraction (p-XRD), high-resolution electron microscopy (HRSEM) with energy dispersive spectroscopy (EDS) analysis and transmission electron microscopy (TEM) before investigating the performance for hydrogen storage. It was observed from the results obtained that the synthesized graphene contains thin stacked flakes of shapes having a well-defined multi-layered structure at the edge. And the round shaped Ni nanoparticles of 13 nanometres in size were dispersed around the graphene structure. The hydrogenation capacity of the Ni/graphene nanocomposites were tested using thermogravimetric analysis (TGA). The prepared Ni/graphene nanocomposites exhibited good hydrogen storage capacities.
Influence of Heat Treatment on Microstructure and Mechanical Properties of Ni-Fe-Co Ternary Alloy Prepared via Spark Plasma Sintering
Authors: Bopape I M C , Shongwe M B , Ogunmuyiwa E N , Rominiyi A L , Jeje S O
Published: November 2019

The use of nickel-based superalloys has extended to different fields such as turbines, rocket motors, chemical equipment, space vehicles and power plants due to their excellent mechanical properties. This study investigates the effect of heat treatment on the microstructure and microhardness of spark plasma sintered Ni-Fe-Co ternary alloy. 50wt.% Ni and varying percentages of Fe and Co powders were milled and fabricated by Spark Plasma Sintering (SPS) technique at a temperature of 900 °C, pressure and holding time were kept at 50 MPa and 10 min respectively. The sintered compacts were heat-treated at 1000 °C, soaked for 1 hr and quenched in distilled water for 5 min. Subsequently, the sintered and heat-treated samples were characterized by scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS) and X-ray Diffraction (XRD) to determine the microstructural evolution and phase transformation accompanying the process. XRD results revealed the evolution of strengthening phases in the heat treated of the samples. The as-sintered and heat-treated compacts Vickers hardness was also investigated before and after the heat treatment. The results show a general improvement in the microstructure after the heat treatment which translated to the observed increase in the hardness of the heat-treated samples.
Effect of nickel powder particle size on the microstructure and thermophysical properties of spark plasma sintered NiCrCoAlTiW-Ta superalloy
Authors: Ogunbiyi O F , Jamiru T , Sadiku E R , Adesina O T , Salifu S A , Beneke L W
Published: November 2019

The spark plasma sintering technique (SPS) was used to consolidate admixed elemental powder in order to fabricate NiCrCoAlTiW-Ta superalloy. Nickel which is the key element that formed the matrix powder particle size was varied in the range of 3-44, 45-106 and 106-150 μm. The effect of varying the starting powder particle size, on the formation of intermetallic phases was investigated. Also, important thermophysical properties in the development of superalloys for high temperature applications were investigated by using laser flash machine, in the range of 100-800 °C. The constituents of the microstructure for the sintered alloy includes, the gamma (γ) matrix phase (Ni), precipitated intermetallic gamma prime (γ’) phase Ni3(Al, Ti) and the precipitated solid solution strengthening elements (Cr and W). There was an increase in the density with decreasing powder particle size. Also, the averave grain size increased with increasing powder particle size. The thermophysical properties obtained, which include thermal conductivity and diffusivity increase with increasing temperature. Non-linear behaviour and inflection points were observed as the temperature increases due to short range order and disorder phenomenon which is associated with superalloys. The powder particle size has little or no significant effect of the thermophysical behaviour as the pattern observed were almost the same.
Fretting Biocorrosion Behaviour of Titanium-Zirconia composites in Foetal Bovine Serum
Authors: Semetse L , Obadele B A , Raganya L , Geringer J , Olubambi P A
Published: November 2019

This work aims at studying the fretting biocorrosion response of newly developed Ti-6Al-4V/ZrO2 in simulated body fluid. Ti-6Al-4V alloy with different volume fractions of ZrO2 produced via powder metallurgy techniques were spark plasma sintered to produce Ti-6Al-4V composites with improved properties. The microstructures of the resulting spark plasma sintered composites were examined using a scanning electron microscope (SEM). Fretting corrosion tests were conducted for each material composition with a special device used for fretting corrosion investigations with a cylinder-on-flat configuration. The tests were done in foetal bovine serum maintained at ambient temperature. Open circuit potential, dissipated energy and coefficient of friction were monitored throughout the experiments. The results show that the microstructures produced after zirconia additions were very different from those observed in pure Ti-6Al-4V. The presence of zirconia promoted the formation of globular zirconia-rich agglomerates throughout the matrix, leading to more improved fretting biocorrosion properties of Ti-6Al-4V.
Prospects of graphite - polypropylene/epoxy blend composite for high performance bipolar plate in polymer electrolyte membrane fuel cell
Authors: Alo O A , Otunniyi I O , Pienaar HCVZ
Published: November 2019

Conductive polymer composites (CPCs) are very promising candidate materials for bipolar plates (BPs) in polymer electrolyte membrane fuel cells (PEMFCs). However, a major challenge facing application of CPCs in PEMFC BPs is the difficulty in achieving high electrical conductivity while maintaining adequate mechanical strength. Therefore, a good balance between electrical conductivity and mechanical strength is critical in the development of high-performance CPC BPs. In this study, CPCs consisting of polypropylene (PP)/epoxy blend filled with graphite were investigated for application as BP material, which will combine electrical conductivity and mechanical strength that meet the performance requirements for PEMFC BPs. The CPCs, with 30 – 80 wt% graphite powder, were produced by melt mixing followed by compression molding. The morphology, in-plane electrical conductivity, and flexural strength of the composites were investigated using the scanning electron microscopy, four-point probe method, and three-point bending test, respectively. The results obtained were compared with the technical targets for PEMFC BPs by the United States Department of Energy (DOE). All the PP/epoxy/graphite composites exhibited flexural strength that satisfies the DOE target of > 25 MPa while the composite with 80 wt% graphite content showed the best in-plane electrical conductivity.
Influence of warm temperature (0.3-0.5Tm) uniaxial compression on the distribution of reinforcing particles in a 2124-Al/10%SiC MMC
Authors: Gxowa-Penxa Z , Chown L H , Govender G
Published: November 2019

Experimental work was carried out to study the influence of uniaxial compression tests, performed on a Gleeble 3500, on the distribution of reinforcing particles in SiC reinforced Al Metal Matrix Composites (MMCs). Al MMC powder (2124-Al with 10 vol. %SiC) was produced through blending in a high energy ball mill. Unreinforced 2124-Al and Al MMC powders were compacted at ambient temperature (i.e. cold compaction) and the green compacts were then sintered at 490°C for 1 hr. Warm temperature (280°C) uniaxial compression tests were performed on a Gleeble 3500 thermomechanical simulator at a strain rate of 5 s-1, strain of 0.3 and a soaking time 20 minutes.

Microstructures of the uniaxially compressed 2124-Al with 10% SiC MMC revealed that deformation had an influence on the distribution of reinforcing particles. Reinforcing particles were only distributed inside 2124-Al grains that had undergone deformation (evident through change in shape of grains). This finding supports statements made in literature regarding the positive influence of deformation on the distribution of reinforcing particles. Engineering stress-strain curves showed that reinforcing 2124-Al with 10 vol. % SiC had a positive effect on flow stress as the 10%SiC MMC had a flow stress of 153 MPa while the flow stress of the unreinforced 2124-Al was 95 MPa. An improvement in hardness was also observed where the MMC had a higher hardness than the unreinforced Al alloy; further indicating that reinforcing the Al alloy improved properties.
The effect of molar ratio and flow velocity on the surface area required for pertraction of a Zr/Hf mixture
Authors: Malan D , van der Westhuizen DJ , Neomagus HWJP , Krieg HM
Published: November 2019

Zirconium (Zr) and hafnium (Hf) need to be separated before being used in nuclear applications. Equilibria data have shown that Hf can be selectively extracted over Zr from a sulphate medium using organophosphorus extractants. This study investigated a modification of Zr and Hf solvent extraction whereby a hollow-fibre membrane contactor was used to separate the aqueous and organic phases, termed pertraction (PX). The aim of the study was to investigate the effects of the molar D2EHPA:Hf ratio and the volumetric flow rate on the estimated surface area required for an industrial PX extraction unit. Equilibrium experiments showed that the maximum separation factor (8.8) was found at D2EHPA:Hf ratio of 350:1. Mass transfer coefficients and kinetic selectivities of hafnium and zirconium were determined using a hollow fibre PX set-up. Variables investigated were: i) D2EHPA concentration, and ii) volumetric flow rate at a constant organic to aqueous ratio. The mass transfer coefficients of hafnium and zirconium and the separation ratio increased at higher flow rates. The best experimental conditions estimate that an industrial extraction unit capable of producing 500 ton per annum nuclear grade zirconium would require approximately 3 200 m2 membrane surface area, at a volumetric flow rate of 1.7 m3.h-1 when operated under similar conditions to those in this study.
Density functional theory study of TiPd alloying with Os as potential high temperature shape memory alloys
Authors: Diale R G , Modiba R , Ngoepe P E , Chauke H R
Published: November 2019

Ti50Pd50 alloy exhibits thermoelastic martensitic phase transformation above 823 K and has the potential for high temperature shape memory material applications. Previous studies showed that this alloy is mechanically unstable with a negative C’ at room temperature. A systematic investigation of the structural, thermodynamic, electronic and elastic properties of TiPdOs is conducted using a first-principles calculation based on density functional theory. The calculated heats of formation show that this compound is thermodynamically stable as Os content is increased. It is found that an increase in Os content stabilizes the TiPd with a positive Cx2032; observed above 18.25 at. %. An increase in Os content results in an increase of the Bulk modulus and Young’s modulus above 18.25 at. %. Anisotropy factor and Vickers hardness are studied and hardness is found to increase with an increase in Os content. The results suggest that the stability of the B2 phase can be significantly enhanced by the addition of Os in TiPd alloy. These findings have important applications for future materials design in aerospace industries.
Exploring the potential of N-acylated chitosan for the removal of toxic pollutants from wastewater
Authors: Naidoo S , Nomadolo N , Matshe W M R , Cele Z , Balogun M
Published: November 2019

Modified chitosan was prepared by chemical derivatisation using caproyl and palmitoyl fatty acid chains. The performance of the materials on the removal of phosphates in aqueous solutions was evaluated through a series of batch adsorption experiments. The phosphate adsorption studies showed enhanced adsorption efficiencies for caproyl chitosan (63%) and for palmitoyl chitosan (71%) in aqueous solutions containing phosphate at a pH of 6.2. The pristine and modified chitosans showed increases in the removal efficiency at an optimal solution pH of 4. The adsorption kinetics studies performed on palmitoyl-chitosan indicated that a contact time of approximately 30 minutes is required to reach equilibrium at solution concentrations ranging from 10-20 mg/l. Co-existing anions such as nitrates and sulphates do affect the phosphate removal efficiency of modified chitosans in aqueous solutions. This study demonstrates that modified chitosans has the potential of being used as a rigid and degradable material for water treatment.
Engineering design highlights of high-efficiency slab casters relocated at Baosteel Zhanjiang
Authors: Ding X L , Feng C B , Liu Q , Yan J W , Zhang Y D , Luo G Q
Published: November 2019

Baosteel Group decided in 2013 to relocate the main segment equipment of the 2 single-strand 2,300 mm slab casters which were shut down at its Luojing Plant to the Zhanjiang Plant and transform them into an upgraded two-strand slab caster. CISDI was contracted to supply the overall design and the main equipment packages. CISDI employed a couple of advanced technologies including online mould width adjustment, top-inserted dummy bar, dual strand tracking and casting at constant speeds to enhance the production capacity of the caster; for sake of Opex saving CISDI also optimized the arrangements of the independent mechanical maintenance shop, utilities of compact design, cooling water valve stations and hydraulic valve stations of compact designs, and open-air cooling water pump station, etc.
Crystallization processes and magnetic properties of FeCoZrMB (M=Nb, V, Cr, Ti) amorphous alloys
Authors: Yu W Q , Lu L P
Published: November 2019

A series of Fe40Co40Zr8M2B10 (M=Nb, V, Cr, Ti, W, Al) alloys were prepared using melt-spinning. The thermal curve, structure and magnetic property of alloys are examined. Because of different negative heat of mixing between elements, only Fe40Co40Zr8M2B10 (M=Nb, V, Cr, Ti) alloys form amorphous structure. These amorphous alloys are annealed at different temperatures under vacuum conditions. The crystallization processes of four amorphous alloys are similar. In the primary stage of crystallization process, only α-Fe(Co) phase precipitates and Co element mainly distributes in the residual amorphous. For the four alloys after annealing at 550°C, there is a few differences in saturation magnetization (
M
s
) and coercivity (
H
c
) due to their different microstructures.
Investigation of temperature and CO2 concentration in converter gas flames by a combustion diagnostic system based on TDLAS
Authors: Liu Y , Wang J S , Xue Q G , Zuo H B , She X F
Published: November 2019

In this study, a novel combustion diagnostic system based on tunable diode laser absorption spectroscopy (TDLAS) was developed to simultaneously measure the temperature and CO2 concentration in flames on a turbulent partly premixed burner. This system simulates harsh industrial combustion environment and enables in situ measurements of non-uniform temperature and CO2 concentration distributions in converter gas-air flames. A mixture of CO, CO2, and N2 with the volume percentage ratio 80:15:5 was injected into the fuel stream to simulate effects of converter gas. Temperature and CO2 concentration in flames along the axial direction at the burner centerline were simultaneously measured by online TDLAS. The flame temperature was compared with that obtained by thermocouple measurement. The CO2 concentration was compared with those of samples taken from the flame. The results of online TDLAS measurements showed the same variation trend as temperature in the core of the flames measured using thermocouples and CO2 concentration obtained from the analysis of samples. This work proved that non-uniform temperature and CO2 concentration distributions in converter gas flames could be measured by this system and laid the foundation for further study about the effects of CO2 and/or N2 addition on converter gas/air flames.