Iron Particle Size Research Articles

A Comparative Study of the Physio-Mechanical Properties of Iron Fillings and Mild Steel Chips in Reinforced Particleboard

This study compared the physio-mechanical characteristics of mild steel chips and iron fillings on sawdust-produced particleboard to regular particleboard made from sawdust alone, using identical production conditions. Particle board was made using 1.18mm sawdust, 3mm mild steel chips, and iron filler with diameters of 0.15mm, 0.425mm, 0.6mm, 1.18mm, and 2.0mm. 70g of sawdust, 40g of iron fillings, and 40g of mild steel chips were used in the production process. 50ml urea formaldehyde was used as a binder. The atomic absorption spectroscopy was determined for iron fillings and mild steel chips. Particleboards were produced at a temperature of 160°C and a pressure of 20 tons for 15 minutes. Mechanical property tested indicates that particleboard containing iron filings has a lower Modulus of rupture (MOR) because the size of the iron filings in the particleboard reduces as the MOR increases. The particle size of iron filling with the value of 2.0mm had the least MOR of 3.99mpa/m2 in iron filling samples. The MOR of Mild steel chips was higher compared to all the samples analyzed. Modulus of Elasticity (MOE) of particleboard produced from iron filings increases as the particle sizes of iron filings increases. The samples containing iron filings alone showed the highest MOE of 244.89 MPa/m2 for 2.0 mm particle board, while the ones containing mild steel chips had the highest MOE of 282.82 MPa/m2 across all samples, suggesting their strength as reinforcement. The rate of water absorption and thickness of swell of particleboard produced from iron filings increases as the size of the iron fillings increase.

Monitoring of suspended matter in the Dnipro River within Zaporizhzhia city, the main trends of 2022

The article presents the results of monitoring observations on the temporal distribution of the qualitative and quantitative components of the Dnipro River suspended matter within Zaporizhzhia city. The research on the territory of this powerful industrial center of Ukraine with a developed metallurgical complex was carried out from 2015 up to 2019 and from the end of 2021 to the present time. The main task of the research was determining the distribution of iron and a group of heavy metals of anthropogenic origin in the composition of the river suspension, and identifying the connections of their concentrations and forms with the natural conditions of the region. Sedimentary matter from the water flows of Dnipro River within research area was sampled once per month using sedimentary traps developed by authors. The methods of electron microscopy (with microprobe analysis) and laser diffraction analysis were used to study the suspension granulometric and chemical composition in the Center for Shared Use of Scientific Equipment of the IGS NASU. SEM studies were carried using scanning electron microscope SEM JEOL-6490 LV (Jeol Ltd., Japan) with an energy dispersive spectrometer of the X-ray microanalysis system INCA Energy+ (Oxford Instruments plc., Great Britain). Particle size analysis was determined using the laser particle size analyzer Mastersizer 2000 with a Hydro 2000S wet dispersion module (Malvern Ins. Ltd, UK).The study results of the samples taken in the first year of hostilities in Ukraine revealed a number of features which were not observed in the previous series of studies. Those peculiarities are the following ones: reduction in the intensity of sedimentary matter accumulation; decrease of technogenic components in the suspension content (in particular, the amount of ferrous metals, changes in the ratio of condensed and dispersed iron particles of silt size, as well as the component composition of fragments of alloys of non-ferrous and ferrous metals). The obtained results may indicate the sensitivity of the component composition of the suspension to changes in the external environment in general, as well as the significant impact of the anthropogenic component on the distribution of iron in suspended matter.

Preparation of Metallized Pellets for Steelmaking by Hydrogen Cooling Reduction with Different Cooling Rates.

To utilize the sensible heat of hot roasted iron ore pellets with no CO2 emission in the production of metallized pellets for direct steelmaking, the pellets were reduced in H2 during their cooling process with variable cooling rates. When the cooling rate decreased from 5.2 °C/min to 2.0 °C/min, the total iron content, reduction degree, and iron metallization degree of the pellets increased continuously from 74.0 wt%, 52%, and 31.1% to 84.9 wt%, 93.4%, and 89.2%, respectively. However, the compressive strength of the pellets increased initially from 2100 N/p to 2436 N/p and then decreased considerably to 841 N/p. As the cooling rate decreased, more Fe2O3 was reduced to Fe with diminishing FeO and Fe2SiO4. The porosity of the pellets increased from 23.9% to 54.3%, with higher distribution uniformity of pores. The morphology of metallic iron particles also transited from a layered form to a spherical form and lastly to a porous reticular form. Meanwhile, the metallic iron particles in the pellets grew evidently with more uniform distributions. When the cooling rate was 3.7 °C/min, the resulting metallized pellets had the reduction degree of 74.2%, iron metallization degree of 66.9%, and the highest compressive strength of 2436 N/p, in association with the spherical morphology and relatively large size of metallic iron particles.

Toward Metallized Pellets for Steelmaking by Hydrogen Cooling Reduction: Effect of Gas Flow Rate.

This study proposed a strategy to prepare metalized pellets for direct steelmaking by hydrogen cooling reduction (HCR) of iron ore pellets with a focus on the effect of H2 flow rate on the process. It was demonstrated that increasing H2 flow rate could effectively enhance the reduction performance of iron ore pellets. However, due to the influence of the countercurrent diffusion resistance of gas molecules, too high H2 flow rate no longer promoted the reduction of the pellets when the maximum reduction rate was reached. The reduction swelling index (RSI) of the pellets initially increased and then decreased with increasing H2 flow rate. This change was associated with the decreased content of Fe2SiO4 in the metalized pellets and the changes in porosity and iron particle size. The compressive strength (CS) decreased continuously, showing a sharp decline when the H2 flow rate reached 0.6 L/min. It was attributed to the significant increases in porosity and average pore size of the metalized pellets, with the presence of surface cracks. When the H2 flow rate was 0.8 L/min, the metalized pellets had the optimal performance, namely, reduction degree of 91.45%, metallization degree of 84.07%, total iron content of 80.67 wt%, RSI of 4.66%, and CS of 1265 N/p. The findings demonstrated the importance of controlling the H2 flow rate in the preparation of metallized pellets by HCR.

High-temperature heat treatment of hydrogen-reduced bauxite residue-calcite pellets for iron particles growth and separationTraitement thermique à haute température de boulettes de résidus de bauxite et calcite réduites à l’hydrogène pour la croissance et la séparation des particules de fer

ABSTRACT Bauxite residue characterised as a polymetallic source containing iron, alumina, titanium, calcium, silicon and rare earth elements offers an opportunity for reduced waste volume and the recovery of valuable metals. This study focuses on the agglomeration of bauxite residue with calcite, followed by hydrogen reduction at 1000°C. The resulting iron particles in the reduced pellets were initially very small distributed in a porous oxide matrix, posing challenges for physical separation methods. To address this issue, further heat treatments were conducted on the reduced pellets in an argon atmosphere, ranging from 1100°C to 1550°C. Phase analysis and microstructural examinations were performed using X-ray powder diffraction and scanning electron microscopy, respectively. Experimental findings indicate that the size of iron particles in the reduced pellets increases with higher heat treatment temperatures. Up to 1200°C, the oxide matrix remains a solid state, transitioning to a semi-molten and molten state above this heat treatment temperature and complete separation of iron from the oxide matrix above 1500°C. An alkali-leachable phase is present in the reduced pellets, initially in the form of calcium aluminate (mayenite), while above 1400°C, this phase dissociates to form monocalcium aluminate, and complete conversion at 1500°C. As observed in the microstructural analysis, there is an increase in the particle size of iron in both the solid and semi-molten states with an increasing in temperature from 1100°C up to 1300°C. This comprehensive study sheds light on the transformative effects of varying heat treatment temperatures on the composition and microstructure of bauxite residue-based materials.

Acetylene and Ethylene Adsorption during Floating Fe Catalyst Formation at the Onset of Carbon Nanotube Growth and the Effect of Sulfur Poisoning: a DFT Study.

Here, we investigated the adsorption of acetylene and ethylene on iron clusters and nanoparticles, which is a crucial aspect in the nascent phase of carbon nanotube growth by floating catalyst chemical vapor deposition (FCCVD). The effect of sulfur on adsorption was also studied due to its indispensable role in the process and its commonly known impact on metal catalyst poisoning. We performed systematic density functional theory (DFT) computations, considering numerous adsorption configurations and iron particles of various sizes (Fen, n = 3-10, 13, 55). We found that acetylene binds significantly more strongly than ethylene and prefers different adsorption sites. The presence of sulfur decreased the adsorption strength only in the immediate proximity of the adsorbate, suggesting that the effect of sulfur is mainly of steric origin while electronic effects play only a minor role. Higher sulfur coverage of the catalyst surface significantly weakened the binding of acetylene or ethylene. To further investigate this interaction, Bader's atoms in molecules (AIM) analysis and charge density difference (CDD) were used, which showed electron transfer from iron clusters or nanoparticles to the adsorbate molecules. The charge transfer exhibited a decreasing trend as sulfur coverage increased. These results can also contribute to the understanding of other iron-based catalytic processes involving hydrocarbons and sulfur, such as the Fischer-Tropsch synthesis.

Characterizing the response of Timepix solid state detectors to dust impacts

Timepix Solid State Detectors (TSSDs) are used in a range of applications, including high energy particle physics, x-ray imaging spectroscopy, medical imaging, radiation monitors and compact dosimeters. In space sciences, such detectors have been used for characterizing the radiation environments of the Earth and lunar surface. This study is a pilot investigation of the response of TSSDs to high-velocity dust impacts. The setup used for the measurements is a silicon slab with 500μm thickness combined with the Timepix 2 read-out chip with a pixel size of 55×55 μm2. The outer surface of the SSD is coated with a 150 nm thick layer of aluminum to eliminate the sensitivity to light. The dust accelerator facility operated at the University of Colorado is used to expose the TSSD to micron- and sub-micron sized iron particles in a velocity range of 1–10 km/s. A fraction (5%) of the impacting dust particles were detected by the TSSD. The primary mechanism of the detection is through the light generated upon the impact and the charge signal spreads over multiple pixels. The fraction of dust particles kinetic energy that is converted to detectable charge on the TSSD is small, in the range of 10−3−10−6. The largest craters generated by the dust impacts were examined using a scanning electron microscope (SEM). The SEM images confirm that the particles penetrated the aluminum layer and the craters contain iron residue from the dust material. Over the investigated impact parameter range, the TSSD does not suffer a permanent damage from the dust impacts. Due to their small size and relatively low sensitivity to dust impacts, TSSDs could be used as dust detectors only in environments with high dust fluxes (e.g., in cometary trails), or where the precision measurements of the impact location are desired.

Catalytic Decomposition of CH4 to Hydrogen and Carbon Nanotubes Using the Pt(1)-Fe(30)/MCM-41 Catalyst

The catalytic decomposition of CH4 to H2 and carbon nanotubes (CNTs) was investigated regarding Pt(1)-Fe(30)/MCM-41 and Fe(30)/MCM-41 using a fixed-bed flow reactor under an atmosphere. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), and Raman spectroscopy were used to characterize the behavior of Pt(1)-Fe(30)/MCM-41 and Fe(30)/MCM-41. The hydrogen yield of Pt(1)-Fe(30)/MCM-41 was 3.2 times higher than that of Fe(30)/MCM-41. When 1 wt% of Pt was added to Fe(30)/MCM-41(Mobil Composition of Matter No. 41), the atomic percentage of Fe2p increased from 13.39% to 16.14% and the core Fe2p1/2 electron levels of Fe0 and Fe2+ chemically shifted to lower energies (0.2 eV and 0.1 eV, respectively) than those of Fe(30)/MCM-41. The Fe, Pt, Si, and O nanoparticles were uniformly distributed on the catalyst surface, and the average iron particle sizes of the Pt(1)-Fe(30)/MCM-41 and Fe(30)/MCM-41 were about 33.4 nm and 58.5 nm, respectively. This is attributed to the uniform distribution of the nano-sized iron particles on the MCM-41 surface, which was due to the suitable metal-carrier interaction (SMCI) between Fe, Pt, and MCM-41 and the high reduction degree of Fe due to the spillover effect of H2 from Pt to Fe. Pt(1)-Fe(30)/MCM-41 produced multiwalled CNTs and bamboo-shaped CNTs with high crystallinity and graphitization degree using the tip-growth mechanism, with an ID/IG ratio of 0.93 and a C(101)/C(002) ratio of 0.64.

Effect of pore structure on the impact toughness of copper-infiltrated sintered steel

Copper-infiltrated sintered steel is a prominent area of research in powder metallurgy, with a particular focus on enhancing impact toughness. In this study, sintered steels with varying pore structures were prepared using iron powders and infiltrated with copper to investigate their impact toughness. The results indicate a significant improvement in the impact toughness of the sintered steels with concentrated iron particle sizes. The density of the samples increased from 6.85 g cm−3 to 7.55 g cm−3 through copper infiltration. The large copper-phase sample with the particle size of 150 μm exhibits an impact toughness as high as 41.09 J cm−2, and its fracture morphology mainly shows transgranular fractures of large iron particles. It is 1.5 times that of the sample made from commercial iron powders which measured 27.46 J cm−2. This enhancement is primarily attributed to the precipitation of γ-Fe within the large copper phase, thereby enhancing the copper phase and transferring the load into large iron particles. A brief mechanism of γ-Fe precipitation in the large copper-phase has been provided.

Polyethylene Glycol as Surface Modification of Magnetite Nanoparticle Coated Silica a Potentially Hyperthermia Therapy Material

Local hyperthermia therapy is one of the cancer treatments by implementing heat from a temperature of 41-45°C on cancer cells. This method is believed to reduce the risk of normal cells around the cancer cells from dying. The form of hyperthermia therapy itself is in ferrofluid. During its development, superparamagnetic nanoparticles of iron oxide have attracted various studies because of their good magnetic properties and good biocompatibility. However, the poor particle interactions and their tendency to aggregation make coatings on superparamagnetic necessary. Therefore, silica coating on the superparamagnetic surface is carried out to reduce the risk of aggregation and increase the biocompatibility of the material. Polyethylene glycol functionalization was also applied to improve the biocompatibility of the material, as well as being a carrier for ferrofluid. The test was carried out using the magnetite co-precipitation synthesis method and the formation of a sol-gel silica coating. Variations applied in this experiment are the effects of TEOS concentration as a source of silica and the ratio of particles to PEG. The addition of silica was proven to increase the value of the magnetic moment to 51.55 emu/g. The addition of TEOS as a source of silica in iron (III) nanoparticles has an effect on increasing the magnetic attraction, decreasing the surface tension value, reducing particle size, and decreasing the SAR value. Functionalization of polyethylene glycol has the effect of reducing the magnetic moment, increasing and decreasing hydrophobicity, increasing the surface tension value, and reducing the particle size of iron (III) oxide nanoparticles. This shows that magnetic nanoparticles coated with silica with polyethylene glycol functionalization are proven to generate heat when given AC current with the SAR value and the highest temperature is found in iron (III) oxide which gets 3ml silica coating with a PEG ratio of 2:5 at a temperature of 32.2°C. and SAR value of 87.63 W/mg

Metal-organic framework-derived Fe3O4-FeCx catalyst for direct CO2 hydrogenation to light olefins

Converting carbon dioxide into lower olefins (C2=-C4=) through hydrogenation is a crucial chemical reaction that allows for the use of CO2 as carbon source in the production of foundational chemicals. Herein, nitrogen-doped carbon-coated iron-based catalysts were obtained by pyrolysis NH2-MIL-88B under N2 atmosphere. The results show that the catalyst morphology, particle size and Fe phase structure can be controlled by changing the pyrolysis conditions. As the temperature rises, the structure starts to deteriorate, resulting in a gradual increase in the iron content and particle size. Fe3O4 and Fe3C phases appeared in the 350/500 °C two-stage pyrolysis, and the two-stage pyrolysis could effectively alleviate the structural collapse of MOFs precursors during the pyrolysis process. With the catalyst obtained by 350/500 °C two-stage pyrolysis, the conversion of CO2 could reach 35.1% and the selectivity of light olefins reached 37.7% (340 °C, 3 MPa, and GHSV= 5000 mL gcat−1 h−1).

Promotion of medium-chain fatty acids and long-chain alcohols production by zero-valent iron: Effect of particle sizes

The effect of zero-valent iron (ZVI) particle size on biological chain elongation (CE) was explored. The addition of ZVI particles with diameters of 50 nm-1000 µm stimulated both medium-chain fatty acids (MCFAs) and long-chain alcohols (LCAs) production, and increased carbon conversion rate of CE process by 2.8–12.2 times. ZVI particle size of 75 µm exhibited the best performance in promoting MCFAs production, achieved the highest MCFAs production of 2164.2 mg/L, which was 11.9 times of control group. ZVI particle size of 1000 µm showed the best performance in stimulating LCAs production, obtained the highest LCAs production of 434.0 mg/L, which was 33.4 times of the control group. Microbial community analysis suggested that different ZVI particle sizes significantly affected genus Clostridium_sensu_stricto_12 and Clostridium_sensu_stricto_7. Functional enzyme analysis revealed that 75 µm ZVI particles induced the strengthened reverse β oxidation pathway, while 1000 µm ZVI particles enhanced the fatty acid biosynthesis pathway.

Shape-Controlled Iron-Paraffin Composites as γ- and X-ray Shielding Materials Formable by Warmth-of-Hands-Derived Plasticity.

The design of shielding materials against ionizing radiation while simultaneously displaying enhanced multifunctional characteristics remains challenging. Here, for the first time, we present moldable paraffin-based iron nano- and microcomposites attenuating γ- and X-radiation. The moldability was gained by the warmth-of-hands-driven plasticity, which allowed for obtaining a specific shape of the composites at room temperature. The manufactured composites contained iron particles of various sizes, ranging from 22 nm to 63 μm. The target materials were widely characterized using XRD, NMR, Raman, TGA, SEM, and EDX. In the case of microcomposites, the shielding properties were developed at two concentrations: 10 and 50 wt %. The statistically significant results indicate that the iron particle size has a negligible effect on the shielding properties of the nano- and microcomposites. On the other hand, the higher iron particle contents significantly affected the attenuating ability, which emerged even as superior to the elemental aluminum in the X-ray range: at a 70 kV anode voltage, the half value layer was 6.689, 1.882, and 0.462 cm for aluminum, paraffin + 10 wt % Fe 3.5-6.5 μm, and paraffin + 50 wt % Fe 3.5-6.5 μm microcomposites, respectively. Importantly, the elaborated methodology-in situ cross-verified in the hospital studies recording real-life sampling-opens the pathway to high-performance, eco-friendly, lightweight, and recyclable shields manufactured via fully reproducible and scalable protocols.

Tribological Characteristics of Rotary Vane Steering Gear Seals Under the Oil With Different Abrasive Particle Sizes

Abrasive particles often cause wear of the rotary vane seals during an operation process, and lead to seal failure and mechanical fault. Focusing on the wear mechanisms and extracting the tribological information during the friction are the prerequisites for extending the service life and carrying out the fault diagnosis prediction of rotary vane seals. Four different sizes of iron particles were selected to mix with the same volume of hydraulic oil to explore the effect of lubricating oil containing abrasive particles on the wear behaviors of the seal. The tribological behaviors during friction were comprehensively analyzed, including the coefficient of friction (COF), wear volume, surface topography, vibration, noise, and other information. The results demonstrated that the wear characteristics of the seal’s contact surfaces changed obviously. The wear morphologies, coefficients of friction, surface roughnesses, and vibration signals increased with the increase of the abrasive particles’ size, with the wear state gradually worsening. When the iron particle size reached 160 μm, the COF increased by 0.047, and the peak vibration signal increased from 4.31 to 36.97 m/s2, compared with pure hydraulic oil lubrication. This tribological information could disclose the wear mechanisms of thermoplastic polyurethanes (TPU) and reveal the TPU wear states. Determining the tribological information for the rubbing pairs was a potential and effective way for evaluating or predicting the rotary vane steering gear seals’ wear states or failure modes. This study lays the foundation for understanding the wear mechanisms and the fault diagnosis of steering gear seals.

Multi-Channel Dual-Mode Oil Multi-Pollutant Detection Sensor

In order to realize the lubricant fluid condition monitoring of ships and offshore engineering equipment, a multi-channel, dual-mode oil multi-pollution detection sensor is proposed and fabricated. The sensor has three detection channels connected via tee tubes, as well as two different detection modes, inductive and capacitive, respectively. In comparison to the traditional sensor, this sensor not only has the ability to distinguish and identify a diverse range of pollutants, but it also experiences an 11-fold increase in its volume of flow, resulting in a significant enhancement in detection efficiency. The mechanism of the inductive and capacitive modes for the differentiated detection of multiple pollutants is elucidated through theoretical analysis. The performance of the sensor is investigated using the constructed experiment platform. The experimental results show that the sensor can realize the simultaneous detection of metallic and non-metallic contaminants in lubricating oil fluids. It can detect the smallest iron particle size of 54 μm, the smallest copper particle size of 90 μm, the smallest water droplet size of 116 μm, and the smallest air bubble size of 130 μm. A novel approach for achieving ship and marine engineering equipment health monitoring and fault diagnosis is presented in this study.

Field experiment pitting magnetite nanoparticles against microparticles: Effect of size in the rehabilitation of metalcontaminated soil

ABSTRACT A significant portion of the current knowledge regarding the use of iron nanoparticles for remediating metal-contaminated soils is derived from laboratory experiments, leaving several unanswered questions. This article presents a field experiment comparing the efficacy of magnetite nanoparticles and microparticles for the immobilization of metals and the growth of plants in metal-contaminated soils. This study aimed to investigate the effects of magnetite particle size on metal immobilization and plant growth in soils exposed to airborne pollution from the Middle-Urals Copper Smelter in the southern taiga subzone near Revda, Russia, 50 km from Ekaterinburg. Magnetite nano- and microparticles were added to forest litter at a 4 % w/w dose. The total metal contents in litter from the study plots were 1-2 orders of magnitude higher than background metal concentrations. The magnetite nanoparticle treatment was found to decrease the concentration of exchangeable copper in soil and improve the growth of red fescue (Festuca rubra L.) on polluted soil compared to the control. In contrast, magnetite microparticles did not show any statistically significant effects. These findings are in line with laboratory results that demonstrated the superior metal adsorption properties of magnetite nanoparticles compared to microparticles. However, this study was limited in duration (2 months), and longer field studies would be necessary to confirm the role of iron particle size in the rehabilitation of metal-contaminated soils.

Highly dispersed Fe/EG catalysts assisted by ammonium citrate and their application in CO2 hydrogenation to olefins

This study employed ammonium citrate as a small molecule additive to modulate the structure of the expanded graphite-loaded iron-based catalyst and its performance in CO2 hydrogenation to olefins. Through catalytic activity, the optimal performance was determined for a 1:1 M ratio of ammonium citrate to Fe salt precursor. The addition of ammonium citrate facilitated the dispersion of Fe particles by increasing the steric hindrance between Fe3+ and anchoring the Fe particles with amorphous carbon generated during calcination, resulting in a decrease in the particle size of iron particles from 20 to 45 nm to 12–27 nm. Furthermore, the nitrogen doping of the support was increased from 0.56% to 2.57%, which provided a strong electron-donating effect and facilitated the reduction and carbonization of iron species. The space time yield (STY) of light olefins was raised from 432.6 mg·gFe-1·h−1 to 604.1 mg·gFe-1·h−1, with a maximum O/P of 5.7. These results demonstrate the effectiveness of using ammonium citrate as an additive for improving the performance of expanded graphite-loaded iron-based catalysts in CO2 hydrogenation to olefins.

Monitoring of the Fe2O3 Particle Size Distribution by Intensity in the Context of Digital Company

This research studies monitoring of Fe2O3 iron particle size produced in industrial companies on the premises of a hot rolling mill. The analysis used the distribution curve method - particle size distribution by intensity. This method determined which particles occur most often in the sample, what is the average particle size, smallest and largest particles. Digitization of individual procedures and monitoring of technological processes provides data that can be worked with at a given time.The obtained data represent a source of information for their further processing in the field of maintenance prediction.

Selective laser melting of oxide dispersion strengthened MA956 alloy and its surface finishing by magnetic field assisted finishing

Selective laser melting (SLM) is a prominent metal additive manufacturing (AM) capable of processing a myriad of engineering materials with high precision and design freedom. However, similar to other AM processes, poor surface finishing has been an omnipresent problem in SLM technology. In this study, magnetic field assisted finishing (MAF) was used to finish SLM fabricated oxide dispersion strengthened (ODS) MA956, an iron‑chromium‑aluminum alloy. The effect of laser processing parameters on part density and surface roughness was first studied. Using a multi-objective optimization technique, the optimal parameters to obtain the highest density and lowest surface roughness were determined. Finally, MAF was applied to the parts built with the obtained optimal SLM parameters, but without significant improvement on the surfaces of as-printed samples. Hence, the surfaces of as-printed samples were post-processed (ground) to yield better initial surface conditions prior to MAF. The effect of initial roughness, iron particles size, and abrasive size on MAF performance was studied. Initial roughness had the most dominant effect followed by abrasive size. The underlying mechanism behind the dependency on initial roughness on final surface quality was analyzed by studying the change on the surface profiles with different starting initial roughness. The initial roughness required for MAF to be effective was determined. Using the optimal processing conditions, MAF was applied to the post-processed samples to attain the final average surface roughness (Ra) as little as 0.36 μm starting from initial average roughness (Ra) of 1.53 μm.

Influences of abrasive particles on tribological behaviours of rotary vane steering gear seals under oil

The wear particles often cause the abnormal wear processes to the rotary vane seals, which lead to seals failure and dropping hydraulic oil pressure, and eventually result in losing of the function of rotary vane steering gear. Clarifying the friction and wear mechanisms between the vane seals and the cylinders and extracting their key wear characteristics are the keys to extend the service life and realize intelligent fault diagnosis of the rotary vane steering gears. Different kinds of hydraulic oils mixed up with different sizes of iron particles were chosen to investigate the abrasive particles on the wear behaviours between the polyurethane polymer and carbon steel specimens. The wear characteristics such as coefficients of friction (COF), wear morphologies, frictional-induced vibration signals were examined and analyzed synthetically. The results showed that the coefficients of friction, wear morphologies, surface roughnesses and vibration signals increased as a function of the iron particle sizes, which indicated that the wear state was gradually worsening. The three-body friction and wear mechanisms were disclosed clearly. There was a certain mapping relationship between the wear characteristics and wear states, and sensing the tribological information between the rubbing pairs, including coefficient of friction, abrasive particle size in hydraulic oil, wear morphology, vibration signal and other characteristics, was a potential and effective way for evaluating or predicting the wear states or failure modes of rotary vane steering gear seals. This study provides a theoretical basis for revealing the friction and wear mechanisms of ship rotary vane steering gear seals, and is useful for accomplishing their intelligent monitoring and fault diagnosis.