scholarly journals Research on the Influence of the Manufacturing Process Conditions of Iron Sintered with the Addition of Layered Lubricating Materials on its Selected Properties

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4782
Author(s):  
Wieslaw Urbaniak ◽  
Tomasz Majewski ◽  
Ryszard Wozniak ◽  
Judyta Sienkiewicz ◽  
Jozef Kubik ◽  
...  
Keyword(s):  
Particle Size ◽  
Boron Nitride ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Hexagonal Boron Nitride ◽  
Average Particle Size ◽  
Layered Materials ◽  
Process Conditions ◽  
Average Particle ◽  
Average Grain Size

The purpose of the conducted experiments was to test the selected properties of materials intended for porous sintered bearings containing layered materials in the form of powders with an average particle size of 0.5–1.5 μm, with very good tribological properties. The subject of the research was a sinter based on iron powder with the addition of layered materials; molybdenum disulfide MoS2 (average particle size 1.5 μm), tungsten disulfide WS2 (average particle size 0.6 μm), hexagonal boron nitride, h-BN (average particle size 0.5 and 1.5 μm) with two different porosities. The article presents the results of density and porosity tests, compressive strength, metallographic and tribological tests and the assessment of changes in the surface condition occurring during the long storage period. The use of layered additives allows for an approximately 20% lower coefficient of friction. In the case of sulfides, the technological process of pressing 250 MPa, 350 MPa, and sintering at a temperature of 1120 °C allows us to obtain a material with good strength and tribological properties, better than in the case of h-BN. However, the main problem is the appearance of elements from the decomposition of sulfide compounds in the material matrix, which results in rapid material degradation. In hexagonal boron nitride, such disintegration under these conditions does not occur; the material as observed does not degrade. In this case, the material is characterized by lower hardness, resulting from a different behavior of hexagonal boron nitride in the pressing and sintering process; in this case, pressing at a pressure of 350 MPa seems to be too low. However, taking into account that even with these technological parameters, the obtained material containing 2.5% h-BN with an average grain size of 1.5 μm allowed obtaining a coefficient of friction at the level of 0.41, which, with very good material durability, seems to be very positive news before further tests.

scholarly journals Rapeseed oil additivated with hexagonal boron nitride

2020 ◽  
Vol 12 (2) ◽  
pp. 63-72
Author(s):  
Traian Florian IONESCU ◽  
Adrian-Alin SORCARU ◽  
Dionis GUGLEA ◽  
George Catalin CRISTEA ◽  
Constantin GEORGESCU ◽  
...  
Keyword(s):  
Particle Size ◽  
Friction Coefficient ◽  
Boron Nitride ◽  
Rapeseed Oil ◽  
Mass Concentration ◽  
Hexagonal Boron Nitride ◽  
Average Particle Size ◽  
Average Particle ◽  
Test Parameters ◽  
Tribological Parameters

This paper presents the influence of hexagonal boron nitride (hBN) as additive in refined rapeseed oil in different mass concentration of 0.25%wt, 0.5%wt and 1%wt on the tribological parameters, obtained on a four-ball machine. The test parameters were load: 100 N, 200 N and 300 N and the rotational speed 1000 rpm, 1400 rpm and 1800 rpm, corresponding to the following sliding speed, 0.38 m/s, 0.53 m/s and 0.69 m/s, respectively. The average particle size of hBN is 14 nm. For the tested ranges of the parameters, the additivation of rapeseed oil with hBN does not improve the friction coefficient, but the wear rate of WSD seems to be less sensitive for the more severe regimes when the vegetal oil is additivated.

scholarly journals Effect of Particle Size on Microstructure and Element Diffusion at the Interface of Tungsten Carbide/High Strength Steel Composites

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4164 ◽  
Author(s):  
Hongmei Zhang ◽  
Hongnan Li ◽  
Ling Yan ◽  
Chao Wang ◽  
Fangfang Ai ◽  
...  
Keyword(s):  
Particle Size ◽  
Tungsten Carbide ◽  
High Strength Steel ◽  
Average Particle Size ◽  
High Strength ◽  
Average Particle ◽  
Micro Hardness ◽  
Vacuum Sintering ◽  
Element Diffusion ◽  
Average Grain Size

The microstructure and micro-hardness of tungsten carbide/high strength steel (WC/HSS) composites with different particle sizes were analyzed by optical microscopy (OM), scanning electron microscopy (SEM), ultra-high temperature laser confocal microscopy (UTLCM) and micro-hardness testing. The composites were prepared by cold pressing and vacuum sintering. The results show that WC density tends to increase as the average grain size of WC decreases and the micro-hardness of WC increases with the decrease of WC particle size. The micro-hardness of WC near the bonding interface is higher than that in other regions. When the particle size of WC powder particles is 200 nm, a transition layer with a certain width is formed at the interface between WC and HSS, and the combination between the two materials is metallurgical. The iron element in the HSS matrix diffuses into the WC structure in contact with it, resulting in a fusion layer of a certain width, and the composite interface is relatively well bonded. When the average particle size of WC powder is 200 nm, W, Fe and Co elements significantly diffuse in the transition zone at the interface. With the increase of WC particle size, the trend of element diffusion decreases.

Fabrication of silicon carbide nanoceramics

1996 ◽  
Vol 11 (7) ◽  
pp. 1601-1604 ◽  
Author(s):  
Mamoru Mitomo ◽  
Young-Wook Kim ◽  
Hideki Hirotsuru
Keyword(s):  
Silicon Carbide ◽  
Particle Size ◽  
Deformation Behavior ◽  
Superplastic Deformation ◽  
Average Particle Size ◽  
Liquid Phase Sintering ◽  
Carbide Powder ◽  
Average Particle ◽  
Average Grain Size ◽  
Silicon Carbide Powder

Ultrafine silicon carbide powder with an average particle size of 90 nm was densified by hot-processing with the addition of Al2O3, Y2O3, and CaO at 1750 °C. Silicon carbide nanoceramics with an average grain size of 110 nm were prepared by liquid phase sintering at low temperature. The materials showed superplastic deformation at a strain rate of 5.0 × 10-4/s at 1700 °C, which is the lowest temperature published. The microstructure and deformation behavior of materials from a submicrometer powder were also investigated as a reference.

scholarly journals Study on the Shear Band of Sand with Various Particle Characteristics Using PIV Analysis

2019 ◽  
Vol 92 ◽  
pp. 06005
Author(s):  
Shintaro Kajiyama ◽  
Yukio Nakata ◽  
Ryota Miyamoto ◽  
Masato Taue
Keyword(s):  
Particle Size ◽  
Shear Band ◽  
Inclination Angle ◽  
Average Particle Size ◽  
Average Particle ◽  
Sample Standard Deviation ◽  
Particle Characteristics ◽  
Coral Sand ◽  
Average Grain Size ◽  
Toyoura Sand

The phenomenon of ground undergoing large plastic deformation, leading to collapse, occurs due to the localization of unstable deformation. The investigation of shear band is important in order to understand the destructive phenomenon. Therefore, a series of experiments were conducted on sands with different particle characteristics so that behaviour of the shear band of sand under plane strain compression could be investigated. Specifically, Toyoura sand and two kinds of coral sand, hereafter referred to as coral sand A (with smaller average particle size) and coral sand B (with larger average particle size) were used. The shear band was evaluated using PIV (Partial Image Velocimetry) analysis. As a result, it became clear that the relationship between shear inclination angle and internal friction angle does not hold for the two kinds of coral sand because the shear inclination angle is low. The ratio of the average value of the shear band width to the average grain size at the peak was 10 to 20 times, 7 to 10 times, and 5 to 8 times in the order of Toyoura sand, coral sand A, and coral sand B. The sample standard deviation was 0.1 to 0.9 mm, 0.9 to 1.6 mm, and 1.4 to 1.9 mm.

Process Parameters Optimization of Direct Synthesis Nano Magnesium Fluoride Powders

2012 ◽  
Vol 184-185 ◽  
pp. 1146-1149
Author(s):  
Ping Li ◽  
Hai Yang Wang ◽  
Wan E Wu ◽  
Shuai Ling
Keyword(s):  
Particle Size ◽  
Orthogonal Experiment ◽  
Direct Synthesis ◽  
Average Particle Size ◽  
Parameters Optimization ◽  
Magnesium Fluoride ◽  
Process Conditions ◽  
Average Particle ◽  
X Ray ◽  
Mgcl2 Concentration

To reduce average particle size，magnesium fluoride was directly synthesized from MgF2 and NH4F，the product was characterized by X-ray diffractomer，scanning electron microscopy. Orthogonal experiment was used to explore the influences of factors on the average particle size. Found that the effect order of factors on the average particle size is MgCl2 concentration，NH4F concentration，reaction temperature，reaction time，in the optimization of process conditions，average particle size is 23.1 nm.

Study on the Microstructure and Properties of ZL205A Alloy under Partial Remelting Treatment

2012 ◽  
Vol 538-541 ◽  
pp. 1183-1186
Author(s):  
Min Li ◽  
Lan Rong Cai ◽  
Peng Xin Liu
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Tensile Strength ◽  
Average Particle Size ◽  
Average Particle ◽  
High Tensile Strength ◽  
Microstructure And Properties ◽  
Partial Remelting ◽  
Average Grain Size ◽  
Zl205a Alloy

In this paper, effects of partial remelting treatment on microstructure and properties of ZL205A alloy were studied in detail. The results show that the grain size of ZL205A alloy decreases at different degree. The grain size increases first and then decreases with increasing of returns content. The average grain size of the primary ZL205A alloy was measured to be about 60 μm, and the good result can be got of the ZL205A alloys with the average particle size of α (Al) phase being about 33 μm after adding 20wt.% returns. The ZL205A alloy with 20 wt.% returns has a considerably high tensile strength and yield strength of 525MPa and 445 MPa, respectively, which is much higher than 501 MPa and 421 MPa of primary ZL205A alloy, meanwhile the elongation level is up to14%.

scholarly journals Studying the Crystal Structure, Topography, and Anti-bacterial of a Novel Titania (TiO2 NPs) Prepared by a Sol-gel Manner

2019 ◽  
Vol 16 (4) ◽  
pp. 0910
Author(s):  
Fayyadh Et al.
Keyword(s):  
Particle Size ◽  
Antibacterial Activity ◽  
Titanium Dioxide ◽  
Calcination Temperature ◽  
Sol Gel ◽  
Average Particle Size ◽  
Average Particle ◽  
Gram Negative ◽  
Tio2 Nps ◽  
Average Grain Size

In this research, titanium dioxide nanoparticles (TiO2 NPs) were prepared through the sol-gel process at an acidic medium (pH3).TiO2 nanoparticles were prepared from titanium trichloride (TiCl3) as a precursor with Ammonium hydroxide (NH4OH) with 1:3 ratio at 50 °C. The resulting gel was dried at 70 °C to obtain the Nanocrystalline powder. The powder from the drying process was treated thermally at temperatures 500 °C and 700 °C. The crystalline structure, surface morphology, and particle size were studied by using X-ray diffraction (XRD), Atomic Force Microscopy (AFM), and Scanning Electron Microscope (SEM). The results showed (anatase) phase of titanium dioxide with the average grain size of 110 nm at 500 °C calcination temperature, and (anatase- rutile) mixed phase of titanium dioxide with the average particle size of 118.1 nm at 700 °C calcination temperature. The anti-bacterial activity of the synthesis specimens was recorded through the Kirby-Bauer disc method (disc devotion method). The results displayed a pretty excellent antibacterial activity of TiO2 NPs to bacteria strains: Gram positive staphylococcus aureus, gram negative pseudomonas aeruginosa, and "gram negative escherichia coli. The sensitivity of the tested bacteria to TiO2 NPs depends on the oxidation state of the TiO2 NPs, particle size, volume, and the density of the unit cell. The small- average particle size of titanium dioxide particles showed high antibacterial activity against bacteria, while the larger- average particle size of titanium dioxide particles showed less antibacterial activity. The novelty of this production is the manufacturing of a novel kind of TiO2 NPs and achievement its best antibacterial activity.

SiC – Zn Nanocomposites Obtained Using the High – Pressure Infiltration Technique

2006 ◽  
Vol 114 ◽  
pp. 257-264 ◽  
Author(s):  
Anna Swiderska-Sroda ◽  
Grzegorz Kalisz ◽  
Ewa Grzanka ◽  
Stanislaw Gierlotka ◽  
Svetlana Stelmakh ◽  
...  
Keyword(s):  
High Pressure ◽  
Volume Fraction ◽  
Continuous Process ◽  
Average Particle Size ◽  
Secondary Phase ◽  
Process Conditions ◽  
Average Particle ◽  
Powder Morphology ◽  
Pressure Infiltration ◽  
Average Grain Size

Two-nanophase SiC-Zn composites were synthesized under pressure up to 8 GPa at up to 1000oC using an high-pressure infiltration method. The advantage of this technique is that in a single, continuous process the ceramic nanopowder is compressed to form the matrix with nanopores; the nanopores are filled with a liquid secondary phase, (here Zn), which crystallizes as nano-scale grains. The key limitation is that the pores in the infiltrated preform have to stay open during the entire process. For this reason only powders of very hard ceramic materials can be used as a matrix. Two types of SiC nanopowders with average crystallite size of 10 nm and 60 nm and average particle size of 30 nm and 100 nm, respectively were used. The measurements of porosity of the green compacts prepared from these powders, pressed at 2.5 GPa and 8 GPa at room temperature, indicated that open porosity was maintained. The nanocomposites obtained show a “nano-nano” type microstructure with a uniform mixture of SiC and Zn phases. The volume fraction of Zn is 20 % independent of the process conditions and initial powder morphology. The process parameters and powder granularity influenced the crystal size of the secondary phase. The average grain size of Zn varied from 20 to 85 nm and was smaller in the composites obtained with the finer matrix, under higher pressure and at lower temperature. The microhardness HV02 of SiCZn nanocomposites varied from 6 to 22 GPa and increased with an increase of pressure and temperature of the infiltration process, and was significantly larger for the finer grained composites.

scholarly journals Preparation of Spherical Sub-Micron Alumina from Hainan Kaolin

CONVERTER ◽  
2021 ◽  
pp. 317-325
Author(s):  
Kai Xu, Jiafei Li, Yongming Zhang
Keyword(s):  
Particle Size ◽  
Uniform Design ◽  
Average Particle Size ◽  
Acid Leaching ◽  
Optimization Method ◽  
Source Material ◽  
Process Conditions ◽  
Alumina Powder ◽  
Average Particle ◽  
Uniform Dispersion

It is an effective way to prepare alumina by replacing bauxite with aluminous minerals. It was studied that the preparation of spherical sub-micron alumina from Hainan kaolin by alginate assisted dispersion. The results of the experiment showed that the alumina content in Hainan kaolin is more than 38%. The t process parameters as of extracting alumina by acid leaching were optimized by uniform design optimization method. The alumina extraction rate reached more than 97% with optimized process conditions. It was used as aluminum source material that he aluminum salt obtained from Hainan kaolin was treated with impurity removal. With this source material, and the purified alginate AG was used as dispersant，the α- Alumina powder with good sphericity, uniform dispersion and average particle size of about 350 was prepared.

scholarly journals Production of fine zinc borate in industrial scale

2012 ◽  
Vol 18 (4-1) ◽  
pp. 547-553 ◽  
Author(s):  
Gaye Çakal
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Scale Up ◽  
Lag Time ◽  
Pilot Scale ◽  
Zinc Borate ◽  
Industrial Scale ◽  
Process Conditions ◽  
Average Particle ◽  
Scale Production

In this study, zinc borate production in an industrial scale batch reactor was carried out at the optimum process conditions determined in the previous studies performed at the laboratory and pilot scale reactors. The production was done via the heterogeneous reaction of boric acid and zinc oxide. The samples were characterized by chemical analysis, XRD, TGA, SEM and particle size distribution. The final product which was obtained in the industrial scale reactor was 2ZnO.3B2O3.3H2O. The kinetic data for the zinc borate production reaction fit to a modified logistic model where the lag time was taken into account. As observed, the reaction time was influenced by scaling up. There was a lag time of 120 min for the industrial scale production and thus, the reaction completion time was 70 min longer compared to pilot scale. It should be emphasized that the specific reaction rate, k; as well as the average particle size and the hydration temperature of zinc borate are unaffected by scale up.

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