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1

Effects of thermo-chemical treatment and grinding process of external cylindrical surfaces on residual stresses in 13CrMo4-5 steel

Wójcik R., Sawicki J.

Journal of Achievements in Materials and Manufacturing Engineering

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2023

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Vol. 120, nr 1

10--21

EN

Purpose This paper presents a study aimed at determining the effect of the carburizing treatment process and the subsequent grinding process on the residual stresses occurring in ring-shaped specimens made of 13CrMo4-5 steel. Design/methodology/approach During the tests, vacuum carburizing was used, achieving an effective case depth ECD = 0.5 mm. Subsequently, the cylindrical outer surfaces of the samples were ground by conventional plunge grinding and with innovative kinematics using a test stand based on a conventional flat-surface grinding machine. As part of the study, microhardness and residual stresses were measured before and after grinding. Measurements were carried out to a depth of 1 mm. The main component of the stand is an original special device that allows the cylindrical specimen to be clamped. Then the angle between its axis of rotation and the axis of rotation of the grinding wheel is set with respect to the plane of the grinding machine’s magnetic table. In the described tests, the axis of rotation of the cylindrical specimen was deviated from its original position by 15° and set at an angle of 75° to the axis of rotation of the grinding wheel. The specimens were ground with a grinding wheel of noble electro-corundum marked 38A60K8V. In both kinematic cases of the grinding process, a machining allowance of 0.01 mm was removed. Findings Grinding using innovative kinematics did not cause any significant changes in the microhardness distribution, either for vacuum or conventional carburizing. In addition, residual stress measurements using the Dawidenkov-Sachs method showed that innovative grinding enables a more favourable distribution than those obtained after conventional plunge grinding. Research limitations/implications Further research will focus on, among others, selecting the angular settings of the workpiece axes relative to the grinding wheel axes depending on their dimensions. Grinding guidelines should include coverage ratio, infeed value, grinding time, and peripheral speeds. In addition, the plan for future research includes measuring the components of the grinding force and the geometric structure of the surface. Practical implications Grinding process is a crucial stage of steel treatment in almost every industrial branch. In sustainable manufacturing, it is extremely important to produce high-quality items while reducing the cost of manufacturing and taking care of the environment and workers’ health. Originality/value The proposed test stand, together with the authors’ device, makes it possible to conduct machining of the external surfaces of cylindrical workpieces on a flat surface grinder. In this case, the innovation of the grinding process consists of the non-parallel alignment of the cylindrical rotational axis of the specimen and the rotational axis of the grinding wheel with respect to the plane of the magnetic grinding table.

2

Low-pressure ferritic nitrocarburizing: a review

Taczała-Warga J., Pawęta S.

Archives of Materials Science and Engineering

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2023

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Vol. 119, nr 2

62--70

EN

Purpose: The purpose of this article was to present in a concise and organized way the available knowledge about ferritic nitrocarburizing in low-pressure. The authors aimed to indicate the research gap, and the whole article is a starting point for further research. Design/methodology/approach: The research method was the analysis of available literature, patent database and industry notes from manufacturers of modern furnaces. Findings: The ferritic nitrocarburizing process has many advantages in line with the market demand and the lack of solutions. The article summarizes the knowledge in the field of the ferritic nitrocarburizing process as a systematization of knowledge and a starting point for further research. Research limitations/implications: The information described in the article requires further laboratory research. Practical implications: The information collected by the authors was the basis for developing the technology discussed in the LIDER/3/0025/L-12/20/NCBR/2021 project. Originality/value: Research on this type of treatment will enable the development of technology and will meet the expectations and needs of the industry. It will also provide benefits in the form of a better understanding of the processes and the determination of the relationship between the parameters and the properties of the obtained surface layers.

3

Effect of grinding conditions of gears made of 20MnCr5 steel after single-piece flow heat treatment on the condition of the surface layer of the tooth working surface

Stachurski W., Janica J., Januszewicz B., Pawłowski W., Sawicki J.

Archives of Materials Science and Engineering

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2023

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Vol. 120, nr 2

60--69

EN

Purpose: The paper investigated the effect of selected processing conditions during gear grinding on the value and distribution of microhardness and residual stress formed in the technological surface layer of gears after thermochemical treatment (TCT) conducted by a continuous single-piece flow method. Design/methodology/approach: The gears were carburised with LPC at 920°C, then quenched in a 4D Quenching chamber at 7 bar and tempered at 190ºC for 3 hours. In the next step, the working surfaces of the gear teeth were ground by supplying grinding fluid (GF) to the grinding zone using the WET method and the MQL method with a minimum amount. Measurements were made on the distribution of microhardness and residual stress formed in the technological surface layer of gears after thermochemical treatment and after the grinding process. Findings: The results of the study showed the influence of workpiece speed vw and the method of delivery to the grinding zone GF on selected parameters describing the condition of the technological surface layer of the teeth of gears made of 20MnCr5 steel. The grinding process with a white aluminium oxide grinding wheel causes deterioration in the material's residual stress state. For each of the three analysed workpiece speeds vw, smaller changes in microhardness with respect to the microhardness of the material before grinding occur in the surface layer of samples ground with GF fed with the MQL method. Similarly, residual stress values are in the area of favourable compressive stresses. Research limitations/implications: Environmental considerations and the need to comply with increasingly stringent environmental protection and worker safety regulations are pushing researchers and entrepreneurs to completely eliminate or reduce the consumption of grinding fluids in the grinding process. Based on the research and analysis carried out in this study, it was concluded that applying minimum GF by the MQL method could be an alternative to the conventional WET method.Practical implications: In sustainable manufacturing, it is extremely important to produce high-quality items while reducing the cost of manufacturing and taking care of the environment and workers' health. This includes the manufacture of gears, a basic component used in gear transmissions in the automotive industry, for example. The research has established that it is possible to use the MQL method, which reduces the amount of GF used when grinding the working surfaces of gear teeth, as an alternative to the conventional WET method. Originality/value: The conducted research was the first to determine the most favourable conditions, in terms of the obtained residual stresses and microhardness, for grinding the working surface of gear teeth using the MQL method.

4

Surface Treatment for Improving Selected Physical and Functional Properties of Tools and Machine Parts — A Review

Toboła Daniel, Kalisz Janusz, Czechowski Kazimierz, Wronska Iwona, Machynia Zbigniew

Journal of Applied Materials Engineering

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2020

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Vol. 60, iss. 1

23--36

EN

Wear resistance, which is one of the main technological quality features of machine parts and tools, is determined by the properties of their surface layer. The demand for high-quality products forces manufacturers to use modern structural and tooling materials as well as efficient and cost-effective methods of their treatment. The paper presents the results of research on selected properties of tools made of tool steels and sintered carbides, as well as parts made of aluminum alloy subjected to selected surface treatment processes, such as mechanical (grinding, turning, milling, burnishing) and thermo-chemical (nitriding, sulfonitriding) processes, and physical vapor deposition (PVD) of coatings. The presented results, including analyses of the surface geometric structure, microstructure, and microhardness, as well as tribological and machining properties of selected materials, indicate the possibility of improving the functional quality of tools and machine parts.

5

The influence of hardening medium in the vacuum carburizing process on the distortion of machine elements used in the automotive industry

Pawęta S., Pietrasik R.

Journal of Achievements in Materials and Manufacturing Engineering

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2019

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Vol. 94, nr 1-2

32--40

EN

Purpose: As part of this study, the influence of the hardening medium on distortions of FineCarb® carburized rollers used in the automotive industry as elements of fuel pumps has been examined. The analysis was carried out for the process of quenching in gas at different pressure of cooling gas and quenching in oil at variable delay time of oil mixers. Design/methodology/approach: The research was carried out on real elements used in the automotive industry as elements of fuel pumps. FineCarb® vacuum carburizing technology was used in order to obtain optimal parameters of the surface layers. During quenching a variable related to the parameters of the quenching medium was introduced. For quenching in gas it was the pressure at which nitrogen was introduced into the cooling chamber, while for quenching in oil it was the time of mixers delay. The sample batch was laid out in accordance with the PPAP (Production Part Approval Process) requirements for the automotive industry. Microhardness and radial runout measurements were carried out on the samples and subjected to statistical analysis. Findings: The analysis of each hardening processes has showed that depending on the cooling medium used, different distortion values are obtained. The distortion value is significantly influenced by the parameters of the hardening process - gas pressure/oil mixers delay. With the proposed quenching parameters, there is no relationship between the location of the sample in the furnace chamber and the distortion value. The smallest hardening distortions were obtained as a result of the hardening process in gas at a gas pressure of 3 bar. Hardening in gas was characterized by the smallest scatter values of obtained results of radial runout. Research limitations/implications: Basing on the studies and analyses carried out in this work, it can be concluded that the introduction of gas quenching technology instead of oil quenching technology is justified qualitatively and economically alike. Hardening in gas was also characterized by the smallest scatter values of obtained results of radial runout. This is an extremely important technological and economic aspect, due to the cost of grinding processing. Practical implications: The automotive and aviation industries are putting ever greater demands on the quality of manufactured components while reducing costs. It requires optimization of technological processes from co-operators. In the case of hardening plants, the most important aspect is obtaining repeatable, precisely planned parameters of the carburized layer, as well as minimizing the negative phenomena that cause dimensional changes after hardening of elements. The tests allowed to determine the most effective hardening conditions in terms of obtained distortions and costs of eliminating distortions. However, the selection of the optimal parameters depends on whether the core hardness requirements are also determined. Originality/value: The conducted tests allowed to determine the most effective hardening conditions in terms of obtained distortions, costs of levelling distortions and a complete technological process for the automotive industry.

6

The Effect of Non-Metallic Inclusions Formed as a Result of Deoxidation on the Fatigue Strength of 15CrNi6 and 16MnCr5 Steel

Lipa S., Sawicki J., Dybowski K., Pietrasik R., Januszewicz B.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1345--1350

EN

This paper presents the findings of fatigue strength tests of 15CrNi6 steel following low-pressure carburizing and oil quenching, subjected to cycles of one-sided three-point bending. The fatigue fractures were compared with the results of fatigue strength studies of 16MnCr5 steel following low-pressure carburizing and nitrogen quenching. The fatigue tests for 16MnCr5 steel were conducted as part of a high-cycle resonance test, with a pendular bending load. The study also involved an analysis of the effects on non-metallic inclusions in the structure on the mechanism of fatigue destruction. The inclusions were found to initiate fatigue cracks. In both cases, a similar method of a fatigue fissure initiation was observed, independent of the study method or specimen material.

7

Complex Reagent Efficiency in Reduction of Copper from the Slags in Conditions of the Smelter & Refinery Plant - Głogów

Wołczyński W., Migas P., Bydałek A. W., Najman K., Senderowski C., Kwapisiński P.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 3

86--90

EN

The copper droplets contained in the post-processing liquid slag are subjected to the treatment by the complex reagent. The complex reagent has been recently elaborated and patented in frame of the Grant No. PBS3/A5/45/2015. In particular, the complex reagent is dedicated to the post-processing slags coming from the Smelter and Refinery Plant, Głogów, as a product of the direct-to-blister technology performed in the flash furnace. The recently patented complex reagent effectively assists not only in agglomeration, and coagulation but also in the deposition of the copper droplets at the bottom of crucible / furnace as well. The treatment of the post-processing slags by the complex reagent was performed in the BOLMET S.A. Company as in the industrial conditions which were similar to those usually applied in the KGHM – Polish Copper (Smelter and Refinery Plant, Głogów). The competition between buoyancy force and gravity is studied from the viewpoint of the required deposition of coagulated copper droplets. The applied complex reagent improves sufficiently the surface free energy of the copper droplets. In the result, the mechanical equilibrium between coagulated copper droplets and surrounding liquid slag is properly modified. Finally, sufficiently large copper droplets are subjected to a settlement on the crucible / furnace bottom according to the requirements.

8

Numerical analysis of the effect of nonmetallic inclusionslocation in carburized layer of 16MNCR5 steel on initiation of fatigue cracking

Lipa Sebastian

Advances in Science and Technology. Research Journal

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2018

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Vol. 12, no 3

66--74

EN

This paper presents the results of a numerical analysis of the effect of the position of non-metallic inclusions in a hardened top layer in 16MnCr5 steel on the mechanism of fatigue destruction. An analysis of a hardened layer formed by thermo-chemical treatment using FineCarb® technology was conducted.Non-metallic inclusions formed by deoxidation of steel were studied; they are usually made of calcium and aluminum. Four positions of inclusions in the hardened layer were tested: under the layer, in the middle part of the layer, under the surface and on the border of two sublayers. The results of the FEM analysis were treated as a qualitative analysis. A map of plastic strains around the inclusion under study was observed. The appearance of plastic strains in the area under analysis signaledthe initiation of a fatigue crack. It was observed that the mechanism of destruction depends largely on the distribution of stress in the top layer and on the place where the inclusion is anchored in the layer. Inclusions under the layer were found to be the main cause of the loss of the structural continuity, which explains the most frequent cases of the initiation of fatigue cracks.

9

Technological solutions to extend the operating cycle of tools and industrial machinery

Lukarski Y., Tashev P., Argirov C., Kondov H.

Prace Instytutu Odlewnictwa

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2017

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Vol. 57, no. 4

253--258

EN

One of the most significant problems that engineers and researchers face is the development of technological solutions to extend the exploitation cycle of tools and industrial machinery. The research shows there are a few possibilities to solve this problem: 1. Development of new materials of enhanced working characteristics compared to those currently used. An example of this is the introduction of new metals and alloys in the automotive industry, the mining industry, etc. 2. Preventive processing of assemblies and parts prior to their use consisting mainly in overlay welding with wear resistant layers or thermo-chemical surface treatment of the parts. 3. Recovering assemblies and parts after their resource has been depleted. This is mainly applied in the mining industry, road construction, etc. Worn-out tools are overlay welded and reused. It has been proven that the price of the recovered details is 2 to 20 times lower than that of the new ones. Moreover, it should be pointed out that the recovery saves energy and ore resources and thus a significant environmental impact is achieved.

10

Study on homogeneity and repeatability of single-piece flow carburizing system

Madej A., Brewka A., Wołowiec-Korecka E.

Journal of Achievements in Materials and Manufacturing Engineering

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2017

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Vol. 84, nr 2

68--75

EN

Purpose: The purpose of this paper was to determine the homogeneity and replicability of carburized layers obtained by a continuous single-piece flow method. Design/methodology/approach: A series of 100 gears was carburized under low pressure atmosphere using the single-piece flow method. The microstructures of the obtained carbon layers were investigated. Hardness penetration pattern and carbon concentration profiles were tested. Findings: The findings have shown the validity/correctness of the microstructures of the carburized layers obtained by the single-piece flow method. It has been proved that the carbon layer in every gear is uniform, what confirms that each element is affected by the same process conditions and the gears in the whole series can be precisely reproduced. Research limitations/implications: The short-pulse low-pressure carburizing technology needs further investigation to understand its all mechanisms fully. Practical implications: The single-piece flow method provides the uniform and reproducible carburized layers with the precision magnitude exceeding the abilities of currently used thermo-chemical furnaces. When applying the method it is possible to obtain a uniform carburized case in every single gear from the whole series of elements subjected to the process. Optimized configuration of process parameters and carbon-carrying mixture allows to meet the high expectations of a modern and future industry, what is most crucial in exploiting carburized steel gears. Originality/value: The applicability of the LPC single-piece flow method to a demanding mass production has been verified. The statistical validity of research results of the whole manufactured series of gears is being performed for the first time.

11

Tribologiczna kwalifikacja materiałów na węzły trące maszyn roboczych

Senatorski J., Tacikowski J., Korwin M., Mączyński P.

Inżynieria Powierzchni

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2017

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nr 3

32--37

PL

W artykule przedstawiono wyniki badań tribologicznych oraz badań metaloznawczych zarówno materiałów już stosowanych, jak i przewidzianych do pracy w węźle trącym elementu sprzęgającego ciężarówki. W badaniach przyjęto dwie akredytowane procedury badawcze. Na podstawie uzyskanych wyników wykazano, że użyte do produkcji wymienionych elementów materiały z warstwami dyfuzyjnymi mają większą przydatność w porównaniu ze stosowaną dotychczas ulepszoną stalą współpracującą z brązem.

EN

This article presents the results of tribological and physical metallurgy studies of materials applied and designed to work in a frictional junction of a truck coupling element. In this study two accredited investigation procedures have been adopted. The obtained investigation results have shown the suitability of the applied materials with diffusion layers for these elements, in comparison to the previously applied toughened steel cooperating with bronze.

12

Copper droplets agglomeration/coagulation in the conditions similar to industrial ones

Wołczyński W., Sypien A., Tarasek A., Bydałek A. W.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 1

289--296

EN

The studied copper droplets suspension in the liquid slag came from the direct-to-blister technology developed in the KGHM - Polska Miedź S.A. plants. A treatment by the stimulators and reagents was performed in the conditions delivered / ensured by the BOLMET S.A., Wiechlice. These conditions were similar to those usually applied to the industrial process. Particularly, this treatment was similar, to some extent, to that known for the electric arc-furnace technology employed in the Smelter and Refinery Plant, Głogów. An effectiveness of the newly developed and patented complex chemical/reagent for the copper removal from slag was tested during the treatment. The effect of the liquid slag stirring on the copper droplets self-cleaning was also analysed. The performed test confirmed the effectiveness of the studied complex reagent in agglomeration, coagulation and sedimentation of the copper droplets.

13

Hybrid layer type CR/LPC

Dybowski K., Kowalczyk P., Januszewicz B., Batory D.

Advances in Science and Technology. Research Journal

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2017

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Vol. 11, no 2

23--27

EN

Application of metal coatings and the carburized layer are widely known and readily used for various elements, depending on the application. Metal coatings based on chromium are used in order to increase resistance to wear, corrosion and erosion. The coatings applied by different methods have a significant drawback - they are not well related with the substratum, so there is a risk of cracking or flaking. Any discrepancies and flaws disqualify such a way as to protect the surface. Carburizing processes will be carried out, primarily in order to increase the hardness of the surface layer while maintaining a ductile core of the object. It is likely that the combination of these treatments will provide to increase the hardness of the material. The behavior of the proper order to create hybrid layer ensures the continuity of the resulting layer and its good connection with the steel. The paper presents a hybrid layer consisting of the deposited chrome and PVD in the next stage of low pressure carburizing. Conducted process allows chromium diffusion into the material, the enrichment of the steel and to ensure the continuity of the layer.

14

Distortion of 16MnCr5 steel parts during low-pressure carburizing

Dybowski K., Niewiedzielski R.

Advances in Science and Technology. Research Journal

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2017

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Vol. 11, no 1

201--207

EN

One of the many advantages of low pressure carburizing (LPC) is that it can be combined with high-pressure gas quenching. This makes it possible to achieve workpieces with pure metallic surfaces, less distortion hardening, and, above all, it allows a more reliable and repeatable treatment than conventional oil quenching. This article presents a study of the distortion rate of workpieces carburized at low pressure then quenched in nitrogen at 1.4 MPa. By comparing the distortion which takes place during the carburizing stage only and the carburizing combined with post-carburizing heat treatment it will be possible to assess the distortion rate and its causes at the different stages of the heat treatment process.

15

The Effect of the Quenching Method on the Deformations Size of Gear Wheels after Vacuum Carburizing

Dybowski K., Sawicki J., Kula P., Atraszkiewicz R., Lipa S.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2B

1057--1062

EN

This paper presents a comparison of the deformations and residual stresses in gear wheels after vacuum carburizing process with quenching in high-pressure nitrogen and oil. The comparison was made on a medium-sized gear wheels, made of AMS6265 (AISI 9310) steel. This steel is applied in the aerospace industry for gears. The study has provided grounds for an assessment of the effect of the method of quenching on the size of deformations. Compared to oil quenching, high-pressure gas quenching following vacuum carburizing resulted in more uniform and smaller deformations.

16

Acetylene Flow Rate as a Crucial Parameter of Vacuum Carburizing Process of Modern Tool Steels

Rokicki P., Dychton K.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 4

2009--2012

EN

Carburizing is one of the most popular and wide used thermo-chemical treatment methods of surface modification of tool steels. It is a process based on carbon diffusive enrichment of the surface material and is applied for elements that are supposed to present higher hardness and wear resistance sustaining core ductility. Typical elements submitted to carburizing process are gears, shafts, pins and bearing elements. In the last years, more and more popular, especially in highly advanced treatment procedures used in the aerospace industry is vacuum carburizing. It is a process based on chemical treatment of the surface in lower pressure, providing much higher uniformity of carburized layer, lower process cost and much lesser negative impact on environment to compare with conventional carburizing methods, as for example gas carburizing in Endo atmosphere. Unfortunately, aerospace industry requires much more detailed description of the phenomena linked to this process method and the literature background shows lack of tests that could confirm fulfilment of all needed requirements and to understand the process itself in much deeper meaning. In the presented paper, authors focused their research on acetylene flow impact on carburized layer characteristic. This is one of the most crucial parameters concerning homogeneity and uniformity of carburized layer properties. That is why, specific process methodology have been planned based on different acetylene flow values, and the surface layer of the steel gears have been investigated in meaning to impact on any possible change in potential properties of the final product.

17

System of single-piece flow case hardening for high volume production

Wołowiec-Korecka E., Korecki M., Stachurski W., Zgórniak P., Sawicki J., Brewka A., Sut M., Bazel M.

Archives of Materials Science and Engineering

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2016

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Vol. 79, nr 1

37--44

EN

Purpose: Purpose of this paper is development of single-piece flow system to precision thermal treatment of parts of mechanical gear using a short-pulse low-pressure carburising technology (developed for a new large-chamber furnace). Design/methodology/approach: Sections of the article discuss the novel constructions of the device in which parts being carburised flow in a stream, as well as the low-pressure carburising experiment. Findings: The method has been found proper carburised layers on typical gear used in automotive industry. Research limitations/implications: The short-pulse low-pressure carburising technology needs further investigation to fully understand its all mechanisms. Practical implications: The device resulting from the experiment can be a fully robotised part of a production line which can be included in a system of automatic control of a production process. Originality/value: The device resulting from the experiment is only known solution on the world.

18

Badanie wpływu obróbki cieplnej i cieplno-chemicznej na kształtowanie się odporności na zużycie przez tarcie staliwa stopowego

Budzynowski T., Mazurkiewicz A., Ropelewski Z.

TTS Technika Transportu Szynowego

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2015

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R. 22, nr 12

1802--1804, CD

PL

W pracy przedstawiono wyniki badań dotyczących wpływu obróbki cieplnej i cieplno-chemicznej na kształtowanie się odporności na zużycie przez tarcie staliwa zawierającego chrom w granicach do 4 do 12 % oraz molibden i wanad. Obróbka cieplno-chemiczna dotyczyła azotowania w atmosferach regulowanych w atmosferze amoniaku i zdysocjowanego amoniaku w czasie 20 h w temperaturach 480 i 530 °C. Obróbka cieplna dotyczyła hartowania z temperatury 930 °C z chłodzeniem w oleju, z następnym niskim odpuszczaniem w temperaturze 220 °C. Badanie przebiegu zużycia zrealizowano zgodnie z normą PN–83/H–04302 „trzy wałeczki – stożek”.

EN

In the paper introduced the results of tests influence heat and heat-chemical treatment on the forming of resistance on abrasive wear and cast steels includes Cr, Mo, V. The heat-chemical treatment referring to nitriding in controlled atmospheres with ammonia and dissocia-tioned ammonia in the time 20 h, in temperature 480 i 530 °C. The heat treatment referring hardening from 930 °C with oil-cooled and sequence low-tempering in 220 °C. The testing of course of abrasive wear was realised with conformity of standard PN–83/H–04302 “three rollers – cone”

19

Mechanical strength and reliability of the porous materials used as adsorbents/catalysts and the new development trends

David E.

Archives of Materials Science and Engineering

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2015

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Vol. 73, nr 1

5--17

EN

Purpose: This paper aims to provide an understanding on some aspects of the porous material strength and reliability and to present future trends of the research on the mechanical properties of this solid porous materials. Design/methodology/approach: It shows that a multitest approach must be designed in order to measure the particle strength and then optimise the production process to enhance its strength. This approach combines measurements reproducing the different types of stress generated in the separation or catalytic process with an extensive characterisation of the physical and mechanical properties of the porous solid, such as hardness, fracture toughnes, brittle, crushing, attrition, etc. The methodology outlined here on alumina single particle or bulk goes beyond the common practice of evaluating mechanical strength based on a comparative study using a single-crushing test and a bulk-crushing test. Findings: Some recent developments on the basic mechanics of solid porous materials are shown. The main concepts presented are the brittle fracture which leads to the mechanical failure of the porous materials, the measurement and statistical properties of the strength data, the mechanical reliability of the porous material pellets, the mechanical properties of the adsorbent or catalyst packed beds, etc. The use and use limitations of inorganic binders for increasing the mechanical strength is discussed and the most binder systems are presented. Research limitations/implications: The scientific basis for the issues on the adsorbent/ catalyst mechanical properties calls yet for further elucidation and development. Practical implications: It is pointed out that porous materials used as adsorbents/ catalysts, with a high and uniform distributed mechanical strength are beneficial to industrial, energetic and environmental applications. Originality/value: A new route for improving mechanical strength of adsorbents/catalysts will become an unavoidable task not only for their manufacturing but also for to improve the efficiency of separation and catalysis processes

20

Gravity/buoyancy competition within coagulation of copper droplets in slag

Wołczyński W., Bydałek A. W.

Archives of Materials Science and Engineering

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2015

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Vol. 76, nr 1

35--45

EN

Purpose: A suspension of copper droplets in the slag coming from the direct-to-blister process was subjected to the treatment analogous to that usually applied to the electric arcfurnace process. In particular, recently patented by authors, complex reagent was applied and verified. Design/methodology/approach: The suspension was subjected to coagulation and solidification. Both processes were studied, independently. The suspension of droplets was treated not only by the recently patented complex reagent but by the CaO – industrial compound (in the amount of 5 %wt.) as well, to make comparison between both substances effectiveness. Findings: The observation was focused on the behavior of droplets to conclude whether the droplets are settled on the crucible bottom due to the effect of gravity or pushed to the liquid slag’s surface due to buoyancy force influence. In the case of the patented reagent application, the coagulation mainly was completed by the droplets’ settlement on the crucible bottom. The treatment performed with the use of the CaO – compound promoted the influence of buoyancy force. The coagulated copper droplets were pushed to the liquid slag’s surface. Research limitations/implications: Rest reagents known in the industry practice will be subjected to the analogous analysis in order to make further comparison with the effect of the patented chemical. Practical implications: Conclusion from the performed experiment made in the crucible (laboratory scale) allow to suggest how to improve not only the semi- or fully industrial directto-blister technology but the treatment of the slag in the electric arc-furnace as well.