PIT Process Research Articles

OPTIMIZING CHARCOAL PRODUCTION: A COMPARISON OF THREE WOOD SPECIES AND METHODS

For sustainable forestry management and environmental protection, it is crucial to compare three wood types and processes in order to optimise charcoal production. The purpose of this study was to evaluate the viability of using diverse waste materials and carbonization techniques to produce wood charcoal. The upcountry wet zone and low-country dry zone regions of Sri Lanka provided the samples, which were each repeated ten times and came in three different sample sizes. To make charcoal, these samples were put through the barrel and pit processes. The results showed that the barrel method produced 28% charcoal instead of the 21% produced by the pit method, demonstrating its higher efficiency and cost-effectiveness. This improvement was ascribed to the barrel's enhanced ability to regulate airflow and temperature during pyrolysis. The study emphasizes the use of wood off-cuts and the barrel method to increase efficiency, save costs, and improve charcoal quality. It provides helpful advice for small charcoal producers.

Corrosion and passivation behavior of in-situ TiC reinforced Al0.1CrNbSi0.1TaTiV refractory high entropy alloy coatings via doping C

This work is aimed to explore ways to further improve corrosion properties of single-phase RHEA coating by introducing in-situ TiC phase. Results shown that C/Al0.1CrNbSi0.1TaTiV RHEA coatings exhibited better comprehensive resistance to pitting and general corrosion compared to most of reported HEAs and traditional alloys. The passive film was dominated by a muti-oxide crystalline structure with a thickness of ∼ 11.52 nm. The small-size and evenly distributed TiC phase with most thermodynamically stable could be obtained via doping C and retard the nearby pitting process, improving the pitting behavior and the dense of passive film in 1.0 wt% C coating.

Vole outbreaks may induce a tularemia disease pit that prevents Iberian hare population recovery in NW Spain

Iberian hare populations have suffered severe declines during recent decades in Spain. Between 1970 and 1990s, a rapid increase in irrigation crop surface in NW Spain (Castilla-y-León region) was followed by a common vole massive range expansion and complete colonization of lowland irrigated agricultural landscapes from mountainous habitats. The subsequent large cyclic fluctuations in abundance of colonizing common voles have contributed to a periodic amplification of Francisellatularensis, the etiological agent that causes human tularemia outbreaks in the region. Tularemia is a fatal disease to lagomorphs, so we hypothesize that vole outbreaks would lead to disease spill over to Iberian hares, increasing prevalence of tularemia and declines among hare populations. Here we report on the possible effects that vole abundance fluctuations and concomitant tularemia outbreaks had on Iberian hare populations in NW Spain. We analysed hare hunting bag data for the region, which has been recurrently affected by vole outbreaks between 1996 and 2019. We also compiled data on F.tularensis prevalence in Iberian hares reported by the regional government between 2007 and 2016. Our results suggest that common vole outbreaks may limit the recovery of hare populations by amplifying and spreading tularemia in the environment. The recurrent rodent-driven outbreaks of tularemia in the region may result in a "disease pit" to Iberian hares: at low host densities, the rate of population growth in hares is lower than the rate at which disease-induced mortality increases with increased rodent host density, therefore, keeping hare populations on a low-density equilibrium. We highlight future research needs to clarify tularemia transmission pathways between voles and hares and confirm a disease pit process.

Perencanaan Kebutuhan Pompa Untuk Sistem Dewatering Tambang Emas Desa Bakan Kabupaten Bolaang Mongondow

One of the most frequent problems in open pit mining methods is the presence of water puddles in the lowest elevation of the pit. This often causesthe delay of production activities.Therefore, it is a need to design a good drainage system planning to deal with it. In this regard, pumps were needed. The aim of this research was to determine the of needed pumps and the best type of pumps to remove water in the pit effectively. This research used maps of mining sequence planningwhich would be then analysed with software Surpac 6.5.1.This was to identifythe width of catchment area. Furthermore, the rainfall data wasanalysed using polygon Thiessen method. The next process is to determine the rainfall plan with Gumbel method. Next was to determine the rainfall intensity plan by using Mononobe equations. Following this was determine the total discharge using rational method. Finally, the process was ended with the determining of the pumps type and pumps spesification to dry the water puddles in the pit. the result indicated that in the sump of the 3rd quarter 2020 with 100 l / sec pumping flow, pumping time 14 hours, total head 76.26 m, recommended pump type is a Multiflo MFC 385 with a rotation speed of recommendation per minute of 1400-1500, and an efficiency of 60% -65%. For 4th quarter sump 2020 with 105l / sec pumping discharge, 20 hour pumping time, total head 105,91 m, recommended type of pump is Multiflo MFC 385 with rotation speed recommendation permenit 1600-1700, with efficiency 60%. For the 1st quarter sump 2021 with a pumping rate of 102 l/sec, the pumping time is 20 hours, total head is 122.26 m, the recommended type of pump is Multiflo MFC 385 with a rotation speed of recommendation per minute 1700-1800, with 50% -60% efficiency. It can be suggested that it is necessary to add one more pump, Multiflo MFC 385, for the dewatering pit process.

Electrochemical origin for mitigated pitting initiation in AA7075 alloy with TiB2 nanoparticles

High-strength Al alloys are susceptible to various corrosion degradation, and the notorious pitting process is the major source for catastrophic failures. Recent development of metal nanocomposites may overcome some of these degradation issues, but the mechanism is unclear due to the blurred pitting initiation and evolution. In this paper, we have systematically analyzed the microstructural change induced by TiB2 nanoparticle nano-treating in AA7075 alloy. The pitting initiation process is directly observed, and the high-resolution surface topographies are used to compare pits’ size and density. Pitted surfaces after long-term immersion are characterized by XPS to quantify the surface composition evolution. Considering these distinct microstructures and surface features, a potential-determined electrochemical model has been set up to explain this advantageous role of TiB2 nanoparticles in AA7075, and our results confirm that this understanding is ubiquitous even with other suitable ceramic nanoparticles.

Effect of hydrostatic pressure on the pitting corrosion of 17-4PH martensitic stainless steel

The effects of hydrostatic pressure on the performance of passive film and the pitting growth process of 17-4PH martensitic stainless steel (17-4PH SS) were investigated by electrochemical measurements and stochastic theory. The results revealed that the growth rate and compactness of the passive film were changed by hydrostatic pressure, which inhibited the diffusion of point defects in the passive film and enhanced the protection performance of the passive film. The change of the performance of the passive film affects the pitting nucleation, metastable pitting process and reduces the transition probability from the metastable pitting to the stable pitting, which eventually leads to the decrease of pitting sensitivity of 17-4PH martensitic stainless steel.

Pitting of malaria parasites in microfluidic devices mimicking spleen interendothelial slits

The spleen is a hematopoietic organ that participates in cellular and humoral immunity. It also serves as a quality control mechanism for removing senescent and/or poorly deformable red blood cells (RBCs) from circulation. Pitting is a specialized process by which the spleen extracts particles, including malaria parasites, from within circulating RBCs during their passage through the interendothelial slits (IES) in the splenic cords. To study this physiological function in vitro, we have developed two microfluidic devices modeling the IES, according to the hypothesis that at a certain range of mechanical stress on the RBC, regulated through both slit size and blood flow, would force it undergo the pitting process without affecting the cell integrity. To prove its functionality in replicating pitting of malaria parasites, we have performed a characterization of P. falciparum-infected RBCs (P.f.-RBCs) after their passage through the devices, determining hemolysis and the proportion of once-infected RBCs (O-iRBCs), defined by the presence of a parasite antigen and absence of DAPI staining of parasite DNA using a flow cytometry-based approach. The passage of P.f.-RBCs through the devices at the physiological flow rate did not affect cell integrity and resulted in an increase of the frequency of O-iRBCs. Both microfluidic device models were capable to replicate the pitting of P.f.-RBCs ex vivo by means of mechanical constraints without cellular involvement, shedding new insights on the role of the spleen in the pathophysiology of malaria.

ANALISA UMUR ALAT POTONG MESIN MILLING DENGAN MATERIAL SUS 420

This research was performed on 3 cutting tools which are tool drill 1.8mm, 2.5mm in diameter and tool back chamfer 2.2mm in diameter. Hardness value from each cutting tool was approximately 300 HRC. Meanwhile, material used in this research is SUS 420 that has hardness value 262HRC. To perform cutting on work unit, it was requested higher hardness value for cutting tool compared to work unit (SUS420). Tool drill 1.8mm in diameter was used at first pitting process (rapping), tool drill 2.5mm in diameter was used at second pitting process (finishing) and tool back chamfer 2.2mm in diameter was used at the last pitting process. This research was performed to define the tool life of cutting tools that utilized in milling machine from work unit material SUS 420. From this research, it was expected maximum amount that can be achieved from cutting tools every replacement can be obtained. At the end of study, when the replacement time of cutting tools can be defined, the loss of not good product (because of cutting) can be avoided. Based on the result, tool life of cutting tool was 920 cuttings.

The Application of Electrochemical Noise for the Study of Metal Corrosion and Organic Anticorrosion Coatings: A Review

AbstractThe electrochemical noise technology and its application in the field of corrosion research are described in this paper. First, the concept, measurement method and data analysis of electrochemical noise are introduced. Then, we discuss the judgment of uniform corrosion, local corrosion and passivation through electrochemical noise. At the same time, electrochemical noise can also distinguish different local corrosion forms, such as pitting corrosion and crevice corrosion. Secondly, the mechanism and chemical kinetics of using electrochemical noise to study the pitting process are discussed. For anticorrosion coatings, electrochemical noise can give the corrosion situation and peeling degree under the coating, and then evaluate the anticorrosion performance of the coating. Finally, while discussing the application prospects of the technology, we also point out the ideal assumptions and data reliability problems currently faced by electrochemical noise technology.

Исследование стойкости к высокотемпературной газовой и солевой коррозии жаропрочного интерметаллидного титанового сплава ВТИ-4

We investigated high-temperature gaseous and salt corrosion resistance of heat-resistant intermetallic titanium VTI-4 (ВТИ-4) alloy samples by conducting accelerated cyclic laboratory testing in air, in a NaCl environment, and in a mixture of Na2SO4 and NaCl. While testing the VTI-4 (ВТИ-4) alloy in air, we observed corrosion of a chemical nature and pseudo-parabolic specific mass variation kinetics. After cyclic testing in a NaCl environment at 700 °C the surface of the VTI-4 (ВТИ-4) alloy was covered by a film consisting of two layers: a mixture of Al2O3 and (Ti, Nb)O2 oxides, and a (Ti, Nb)O2 layer. In a NaCl + Na2SO4 environment at temperatures of 650 and 700 °C a liquid ion conductor film may manifest on the alloy surface alongside the oxides, while corrosion becomes predominantly electrochemical, of the pitting type. Globular orthorhombic phase particles initiate the pitting process. We detected that the pit depth in the alloy after testing in a Na2SO4 + NaCl environment at 650 and 700 °C is twice that obtained in NaCl at 700 °C. At the temperatures of 650 °C in Na2SO4 + NaCl and 700 °C in NaCl and Na2SO4 + NaCl environments the specific mass variation becomes negative, which is due to the oxide film peeling and shedding as temperatures change. The corrosion rate for the VTI-4 (ВТИ-4) alloy in the Na2SO4 + NaCl environment at 650 °C is lower than those for the nickel alloys VV751P (ВВ751П) and VZh175-ID (ВЖ175-ИД)

Weak acid leaching of MgB2 to purify magnesiothermic boron powder

We have established a new procedure for recovering boron contained in oxidized MgB2 phase. Incorrect conditions of synthesis or conservation, or excess impurities in precursors, can lead to MgO formation with consequent degradation of superconducting properties, thus representing a possible problem in the industrial production of MgB2 conductors following the ex-situ PIT process. A procedure has been developed in order to dissolve MgO (due to the oxidization of Mg in MgB2 phase) and to decompose the MgB2 phase into elemental B and a soluble Mg salt. The process can also be successfully applied to low-grade B in order to enhance the purity, providing that the B is first reacted into MgB2. In fact, MgB2 synthesis converts residual B2O3 (present in B) and other impurities to leachable compounds. For the present work, an ill-preserved MgB2 powder produced in 2008 was treated with glacial acetic acid. The reduction of impurities and secondary phases was monitored along each step of the proposed process by X-ray diffraction (XRD) technique and by energy dispersion spectroscopy (EDS) analysis. The purification process was successfully applied on two different MgB2 powders: the first was synthesized using commercial B (H. C. Starck), the second using a different magnesiothermic B with a low purity grade prepared by freeze-drying process at CNR-SPIN. An interesting result is that, after acidic treatment of MgB2, the resulting B particles are finer and more amorphous than pristine B particles. The increased surface area of B undoubtedly offers a more reactivity of powders versus the weak acid, because the impurities within the B particles are exposed to the direct action of the acid and not longer protected by B crust.

Honeycomb-like porous metallic glasses decorated by Cu nanoparticles formed by one-pot electrochemically galvanostatic etching

Pitting corrosion is a common localized corrosion phenomenon, which can lead to cracks and mechanical failure in structural metal materials. On the contrary, pitting corrosion could be a beneficial tool for generating large-area porous structures, which holds a great premise in a number of functional services, such as catalysis, sensing, storage, imprint lithography, and membranes. Herein we presents an electrochemical approach for creating a large-area honeycomb-like porous structure in Zr-based metallic glasses. A pitting process followed by subsurface tunnel etching in NaCl solution elicits to characteristic micrometer scale channels and nanometer size amorphous sidewalls decorated by Cu nanoparticles on the metallic glass substrate. A root-shape growing mechanism of tunnels initiated from pits and penetrating into alloy matrix is postulated. In addition, the effect of alloy composition on the microstructure of honeycomb-like porous metallic glasses is also investigated in detail.

Role of Cr-coating by electroplating method on fabrication and transport properties of Fe/Cr/MgB2 wires

This study has focused on the use of chromium metal as a chemical barrier in the production of in situ MgB2 wires. The chromium metal was plated homogeneously into the initial iron tube by electroplating in order to produce in situ mono-core and multi-filamentary Fe/Cr/MgB2 wires. Cr metal has maintained its continuity through the wire drawing, but inhomogeneous thickness of Cr-coating at the Cr/Fe interface region without chemical reaction to each other is revealed. The in situ mono-core Fe/Cr/MgB2 wire with a diameter of 1.32 mm and multi-filamentary wires with 1.00 mm and 1.26 mm diameters were produced by PIT process and heat treated at different annealing temperatures and times. Transport and structural investigations of the wires indicated locally positive effect of Cr-coating on Fe2B phase formation, transport properties, and the core structure of MgB2 wires. The mono-core Fe/Cr/MgB2 wire-coded A24 has the highest engineering critical current density of 56 A/cm2 at 30 K under 6.5 T.

Image-based system and artificial neural network to automate a quality control system for cherries pitting process

This work proposes a non-destructive quality control for a pitting process of cherries. A system composed of a video camera and a light source records pictures of backlit cherries. The images processing in MATLAB environment provides the dynamic histograms of the pictures, which are analysed to state the presence of the pit.A feedforward artificial neural network was implemented and trained with the histograms obtained. The network developed allows a fast detection of stone fractions not visible by human inspection and the reduction of the accidental reject of properly manufactured products.

Stress corrosion cracking mechanism of AISI 316LN stainless steel rebars in chloride contaminated concrete pore solution using the slow strain rate technique

In this work, the stress corrosion cracking (SCC) mechanism of austenitic stainless steel AISI 316 LN rebar is studied along the entire stress-strain diagram by slow strain rate technique. The growth and passivity breakdown of the passive film is proved by non-destructive electrochemical tests as well as by current monitoring. The current density experiences multiple peaks related to the nucleation of metastable pits on AISI 316 LN surface near the yield stress (fy), followed by passivity breakdown of the passive film due to residual stresses, in addition to the chloride pitting process. The activation of dislocations dynamics induces high stress concentration in the passive film after reaching fy stress value, and consequently the development of high oxygen vacancies, increasing the oxygen diffusion, and therefore producing stable pits instead of metastable ones. The addition of 4 wt% Cl− in the concrete pore solution enhances the pitting process leading to film rupture, thus developing a mixed fracture mechanism characteristic of SCC.

Corrosion-Fatigue Evaluation of Uncoated Weathering Steel Bridges

Uncoated weathering steel (UWS) bridges have been extensively used to reduce the lifecycle cost since they are maintenance-free and eco-friendly. However, the fatigue issue becomes significant in UWS bridges due to the intended corrosion process utilized to form the corrodent-proof rust layer instead of the coating process. In this paper, an innovative model is proposed to simulate the corrosion-fatigue (C-F) process in UWS bridges. Generally, the C-F process could be considered as two relatively independent stages in a time series, including the pitting process of flaw-initiation and the fatigue crack propagation of the critical pitting flaw. In the proposed C-F model, Faraday’s law has been employed at the critical flaw-initiation stage to describe the pitting process, in which the pitting current is applied to reflect the pitting rate in different corrosive environments. At the crack propagation stage, the influence of pitting corrosion is so small that it can be safely ignored. In simulating the crack propagation stage, the advanced NASGRO equation proposed by the NASA is employed instead of the classic Paris’ law, in which a modified fatigue limit is adopted. The fatigue limit is then used to determine the critical size of pitting flaws, above which the fatigue effect joins as a parallel driving force in crack propagation. The model is then validated through the experimental data from published articles at the initiation stage as well as the whole C-F process. Two types of structural steel, i.e., HPS 70W and 14MnNbq steel, have been selected to carry out a case study. The result shows that the C-F life can be notably prolonged in the HPS 70W due to the enhancement in fatigue strength and corrosion resistance. Besides, a sensitivity analysis has been made on the crucial parameters, including the stress range, stress ratio, corrosive environment and average daily truck traffic (ADTT). The result has revealed the different influence of the above parameters on the initiation life and propagation life.

Numerical study on steady pitting process of metal surface

Numerical study on steady pitting process of metal surface

Comparison of corrosion behaviors between Ti-based bulk metallic glasses and its composites

The corrosion behaviors of the Ti-based bulk metallic glasses (Zr30.88Ti33.57Cu7Ni5.39Be23.16) as well as the in-situ Ti-based bulk metallic glass matrix composites (Zr28.92Ti42.22Cu6.57Nb6Be16.29) in 0.6 mol/L NaCl, 1 mol/L HCl and 0.5 mol/L H2SO4 solutions were analyzed. The potentiodynamic polarization analyses indicated a drastic increase in the current densities for all specimens in the NaCl and HCl solutions, which could be related to the passive breakdown caused by pitting corrosion. In contrast, no active-passive transition existed in the H2SO4 solution. SEM and EDS analyses were performed to clarify the morphologies and chemical states of the elements prior to and following electrochemical testing. The results demonstrated that both alloys exhibited entirely different corrosion behaviors in the chloride-containing and chloride-free solutions. The surfaces of the samples were locally damaged by a chloride-induced pitting process. Specifically for the composites, a selective dissolution occurred. In contrast, a low portion of corrosion occurred within the chloride-free media. The chemical compositions were identified as the main factor to affect the corrosion performance of the alloys.

Improvement of in-situ Fe/MgB2 monofilamentary wires by internal Mg-coating process

In the present work, we have studied on the use of internally Mg-coated and uncoated iron tubes in processing of in-situ mono filamentary Fe/MgB2 wires by means of transport measurements and structural analysis methods. For coated wires, the starting Fe tube is internally coated by magnesium before PIT process is applied and these wires with 0.81 mm in diameter are heat treated at different annealing temperatures and times. The main idea behind this work is to investigate the possible role of Mg coating on inhibition of Fe2B phase formation and its contribution to granular structure of MgB2 core. The transport and superconducting properties in the presence of external magnetic field are well improved for Mg-coated wire samples in comparison to the uncoated wire samples. The structural and surface analyses of Mg-coated wires reveal that the Fe2B formation still exists at the interface region. The results are interpreted in terms of effects of excess magnesium, internal Mg vapor pressure, homogeinity of Mg coating process, and heat treatment conditions. The highest engineering critical current density Jce(4.2 K) is obtained as greater than 5.4 × 104 A/cm2 at μ0H = 4 T among the coated samples.

Nickel nanoparticles partially embedded into carbon fiber cloth via metal-mediated pitting process as flexible and efficient electrodes for hydrogen evolution reactions

Sunlight-driven electrolytic splitting of water is a promising route to hydrogen production, and widespread implementation has called for the development of inexpensive, robust and large-scale electrodes. Here, nickel nanoparticles partially embedded into carbon fiber cloth (NiΦCFC) is prepared on a large scale (e.g., 40 cm × 40 cm) via a metal-mediated pitting process, which is adopted to fabricate hydrogen evolution reaction electrode for the first time. The partially embedded structure is beneficial for regulating the electron density state of carbon, exposing the nickel catalytic sites and improving the catalytic stability. The two kinds of electrochemical area and density functional theory results confirm that the interface effect between nickel and defective carbon leads into a low Gibbs free energy of H* adsorption. The NiΦCFC as flexible and efficient electrodes require a small overpotential of 131.5 mV to achieve −10 mA cm−2. Note that the two-electrode electrolyzer composed of FeNi layered double hydroxide loaded on CFC (NiFe-LDH/CFC) (+)//NiΦCFC (−) possesses a voltage of 1.54 V at −10 mA cm−2, which can also be powered by a solar cell. The facile and large-scale preparation of NiΦCFC as flexible electrodes could be adapted for the industrial hydrogen production powered by solar energy.