Continuous Airflow Research Articles

A novel method for positive airway pressure delivery: pulsating airflow.

The primary objective is to determine if pulsating airflow can achieve therapeutic pharyngeal pressure levels without requiring a tight-sealing mask. A pilot study included 12 nasal-breathing adults who are currently using positive airway pressure (PAP) for therapy. Patients were awake, and pharyngeal pressures were measured using a miniature pressure probe inserted through their nares. Pulsating airflow was applied via a nasal cannula with a customized valve. The inspiratory flow rate was increased until the pharyngeal pressure matched or exceeded the participant's prescribed PAP level. The expiratory flow rate was maintained at a constant low level of continuous airflow. The study demonstrated that pulsating airflow could generate pharyngeal pressures equivalent to or higher than those achieved with PAP therapy in all participants. The peak inspiratory pressures with pulsating airflow followed an oscillatory pattern matching the pulsation frequency. The mean peak pressure increased linearly with the pulsating flow rate. Compared to a high-flow nasal cannula, pulsating airflow produced significantly higher inspiratory pharyngeal pressures, reaching nearly 20 cmH2O. Pulsating airflow could be a viable method for delivering PAP therapy to patients with respiratory or sleep disorders without needing a tight-sealing mask. Further research is required to establish whether this method can improve patient compliance with PAP therapy, assess long-term safety and efficacy, and explore the impact of varying pulsation parameters on treatment outcomes.

Study on aerodynamic breakup of non-Newtonian liquid droplets and the distribution characteristics of their sub-droplets

In industrial applications, the secondary breakup of droplets and the size distribution of their sub-droplets are crucial for atomization performance indicators. In this work, a high-speed digital camera is utilized to experimentally and theoretically study the secondary breakup process of xanthan gum (XG) droplets and the size distribution changes of resulting sub-droplets in continuous airflow by changing the Weber number and effective Ohnesorge number. In addition, a detailed study is conducted on the liquid ring with the highest liquid content. The results show that at low Weber numbers, the number of nodes generated at the XG droplet ring is the same as that of the water droplet, following “the combined R-T/aerodynamic drag” mechanism. However, the final diameter of the nodes differs significantly from that of the water droplet. The particle size of XG liquid ring nodes is not only affected by the Weber number but also decreases with the increase of the effective Ohnesorge number. The particle size of the remaining broken sub-droplets in the liquid ring decreases with the increase of the effective Ohnesorge number. Finally, the spatial range of droplet breakup under different parameters is described by using the liquid ring breakup angle, and it is found that the breakup angle of the liquid ring is mainly related to the breakup mode.

Oxidation of Airborne m-Xylene in Pulsed Corona Discharge: Impact of Water Sprinkling

Plasma from electric discharges can be used in the abatement of volatile organic compounds (VOCs). The application of gas-phase pulsed corona discharge (PCD) in air–water mixtures provides favorable conditions for the oxidation of VOCs at unsurpassed energy efficiency. This research investigates the impact of water sprinkling on PCD performance in the oxidation of m-xylene as a model compound. Experimental research into the plasma treatment of continuous air flow was undertaken using the PCD reactor in dry and water-sprinkled modes. Water sprinkling more than doubled the m-xylene oxidation rate, which can be attributed to abundant OH-radicals produced at the plasma–water interface. Water sprinkling substantially reduced the formation of nitrous oxide, which is considered to be a secondary pollutant in the outlet air. Ozone is considered a by-product helping the subsequent photocatalytic oxidation of potential residues and photocatalyst maintenance. The use of water-sprinkled PCD is a promising approach to energy-efficient abatement of VOCs.

Long-Term Management of Sleep Apnea-Hypopnea Syndrome: Efficacy and Challenges of Continuous Positive Airway Pressure Therapy

Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS) is a prevalent condition characterized by intermittent upper airway obstruction during sleep, leading to significant health issues, including cardiovascular disease, metabolic syndrome, and neurodegenerative disorders. The primary treatment for OSAHS is Continuous Positive Airway Pressure (CPAP) therapy, which maintains airway patency through a continuous flow of air, effectively reducing apnea-hypopnea indices, improving sleep quality, and lowering cardiovascular risks.

Synthesis of Z-scheme amorphous WO3-loaded TiO2 photocatalyst for enhanced photocatalytic degradation of dichloromethane: Internal electric field and mechanism exploration

Photocatalytic technology is a highly efficient means for treatment of volatile organic compounds (VOCs) and mitigation of environmental issues. In this study, we successfully prepared the Z-scheme WO3/TiO2 heterojunction catalyst through the impregnation sintering process. The photocatalytic performance of dichloromethane (DCM) was examined by monitoring its concentration changes under ultraviolet light irradiation. The results demonstrated that 3 % WO3/TiO2 exhibited the most excellent performance, achieving a degradation performance of 98 % under a continuous airflow of 0.8 L/min and an initial DCM concentration of 200 ppm. Importantly, the catalyst maintained its performance without any significant decrease even after 100 h of continuous testing. The excellent performance was mainly thanks to built-in electric field and narrower bandgap, which effectively reduced electron and hole complexation, thereby increasing the production of more reactive oxygen species. Gas phase capture testing revealed that •O2- radicals played a crucial role in DCM degradation. Additionally, the improvement of surface acidity by WO3 and preferential breaking of C-Cl bond effectively prevented the production of phosgene (COCl2). This research finding addresses the gap in the understanding of photocatalytic degradation of DCM with TiO2 modified by metal oxides and lays a strong foundation for future industrial applications.

A Contrast Experiment on the Ventilation Direction towards Human Head in Personalized Environmental Control System (PECS)

A heating, ventilation, and air-conditioning system is designed for the entire space but falls short in meeting diverse individual needs. Therefore, the personalized environmental control system is proposed to address individual thermal requirements and it has been widely accepted and produced to have significant practical value for humans. In order to enhance the comfort level based on the PECS, the impact of the airflow direction towards the head in terms of physiological and psychological sensations was investigated. Different airflow directions were considered as follows: front blowing (FB-PV), side blowing (SB-PV), back blowing (BB-PV), top blowing (TB-PV), and a control group No-PV. A total of 56 participants were invited to assess the thermal environment, and their skin temperature was measured. The results revealed that the airflow towards the head improved thermal comfort and reduced the mean skin temperature by 0.4–0.6 °C, with FB-PV showing particularly promising results. TB-PV demonstrated the highest level of comfort with a score of +1.05 (slightly higher than “Just comfortable (+1)”) and scored significantly higher in overall willingness at +1.21 (higher than “Willing (+1)”). Conversely, FB-PV resulted in a discomfort level due to restricted breathing under the continuous airflow condition.

ARIMAX Modelling: Response of Hass Avocado Respiration Rate to Environmental Factors

This research explores how random events influence the respiration rate in Hass avocado beyond deterministic models in order to develop better strategies for extending its shelf life. Understanding these factors can enhance the accuracy of postharvest management strategies. The Autoregressive Integrated Moving Average (ARIMA) model with exogenous variables (ARIMAX) is an alternative stochastic probability model which is capable of modeling complex, externally influenced phenomena such as respiration. This study aimed to elucidate the effect of three exogenous variables, namely temperature, relative humidity, and ambient illumination, on the respiration rate of Hass avocado fruits. Data on the respiration rate and exogenous variables were obtained using sensors coupled to a data acquisition system in a prototype of continuous airflow. The Box–Jenkins methodology was employed to construct the ARIMA models. The temperature, relative humidity, ambient illumination, and respiration rate variables were adjusted to the ARIMA models (3,1,2), ARIMA (1,1,2), ARIMA (1,1,2), and ARIMA (1,1,3), respectively. The ARIMAX (1,1,3) models were obtained from the pre-whitened respiration rate series. The impact detected in the transfer functions indicates increases in the respiration rate of 0.34%, 1.52%, and 0.99% for each unit increase in the temperature, relative humidity, and ambient illumination variables, respectively. In this regard, ARIMAX modeling is reliable for explaining the physiological response of Hass avocado fruits due to external factors. In future research, it is intended to extrapolate this stochastic modeling procedure to measure the effect of dynamic loads on the respiratory metabolism of fruits during transportation, where there is a considerable loss in the quality of fresh products.

A novel solid-phase extraction device for the pneumatic cycle pharmaceuticals residues adsorption: A proof of concept study

In this study, a pneumatic cycle device, herein called the air-operated solid-phase extraction (AO-SPE), was designed for the enrichment of pharmaceutical residues. The device consisted of two parts: an air circulation system and an adsorption system. The continuous air flow ensured that the water sample flowed past the adsorbent, completing the adsorption process. One significant advantage of this device is that the air circulation system can generate pneumatic cycle adsorption with the continuous air flow, increasing the interaction between the adsorbent and the target analytes. Additionally, the entire device is easy to install and dismantle, and the adsorbent can be easily replaced, making the AO-SPE suitable for various types of adsorbents materials tailored to specific target analytes. The smart design is aimed at extracting trace analytes in the large-volume water samples. As a proof-of-concept, the AO-SPE was applied to enrich non-steroidal anti-inflammatory drugs in soil. A Ce-based metal organic framework composite was prepared and applied to verify the applicability of AO-SPE, exhibiting the enrichment factor of up to 538. The results showed that AO-SPE exhibited a maneuverable approach with high efficiency and sensitivity for analyzing large-volume samples, indicating a great potential for extracting of trace analytes.

Nocturnal Urinary Symptoms as Screening Tools for Obstructive Sleep Apnea.

Nocturnal lower urinary tract symptoms are part of obstructive sleep apnea (OSA), and urogynecology clinics may serve as OSA screening sites. This study's aim was to determine the accuracy of nocturia and nocturnal enuresis (NE) as screening tools for OSA in new patients at a urogynecology clinic. Using a retrospective study design, we gathered information regarding diagnostic OSA testing, continuous positive airflow pressure use, and lower urinary tract symptoms improvement from women in a urogynecology clinic who were previously screened for OSA using validated questionnaires. Nocturia and NE were tested for sensitivity and specificity using positive OSA diagnosis by polysomnography as the gold standard. Nocturia with a cutoff of ≥2 episodes per night had the best test characteristics-86.4% sensitivity (95% confidence interval [CI], 65.1-97.1) and 58.5% specificity (95% CI, 44.1-71.9) for an overall accuracy of 78.4% (95% CI, 67.0-89.8). Nocturnal enuresis with a cutoff of ≥1 episode per week had the best NE characteristics with 31.8% sensitivity (95% CI, 13.9-54.9) and 79.3% specificity (95% CI, 65.9-89.2) for an overall accuracy of 56.1% (95% CI, 41.2-71). Lower urinary tract symptoms such as nocturia and NE are routinely assessed in urogynecology clinics, making them useful for OSA screening and referral. The present study found nocturia symptoms with ≥2 episodes per night to retain acceptable test characteristics in screening for OSA, whereas NE was found to have less acceptable test characteristics for OSA screening. Urogynecology clinics may utilize nocturia symptoms in clinical decision making for OSA referral.

Long-lasting removal of indoor formaldehyde in continuous airflow by B–TiO2@AC composites

Formaldehyde can cause unacceptable indoor air quality. Traditional adsorption-based materials for indoor formaldehyde removal have the problem of short lifespan and potential secondary pollution. The black TiO2 was synthesized to engineer a material for long-lasting removal in this study, which has a disordered surface layer and defects, resulting in higher light absorption and a narrower band gap under UV and visible light. The novel TiO2 catalyst was composited with different mass fraction of activated carbon to increase active adsorption sites and improve electron transport efficiency. Besides, the formaldehyde decomposition mechanism and kinetics were investigated by material characterization. The performance of the developed material in removing formaldehyde was evaluated using a high-precision, variable-condition continuous flow system designed to simulate actual application environment. B–TiO2@15AC exhibited 1.5 times higher cumulative removal capacity than traditional KMnO4@Al2O3 material after 16h, while maintaining constant efficiency over 40h. Formaldehyde concentration, activated carbon ratio, relative humidity, irradiation wavelength and air flow were chosen as variables and their effect on the removal efficiency was analyzed using Response Surface Methodology. This study presents a promising new material which is low-cost, easy-to-prepare and applicable in indoor formaldehyde removal.

Potencial del arbusto Lantana camara L. (Verbenaceae) para la fitoestabilización y volatilización de mercurio

Mercury (Hg) is the most harmful heavy metal for living beings due to its high toxicity, persistence, and bioaugmentation in the food web. Lantana camara has been considered promising for the phytoremediation of different metals, but its response to Hg has not been characterized. The objective of this study was to evaluate the effectiveness of L. camara to bioaccumulate, translocate, and volatilize Hg in artificially contaminated soils (1.0 and 8.0 mg/kg Hg). After two months of treatment, the dry weight was measured and the Hg present in stems, roots, leaves, and atmosphere was quantified using atomic absorption spectroscopy. The volatilized Hg was captured in hermetic chambers with continuous airflow, connected to a trap solution (5 % KMnO4 dissolved in H2SO4). The translocation factor was < 1, and the bioaccumulation factor was > 1 in both treatments. The Hgº values volatilized in high mercury indicate that approximately 7.1 µg/g plant/day can be released into the atmosphere. Our results indicate that L. camara accumulates Hg mainly in the root, showing potential for phytostabilization, but the observed volatilization rates point towards a more restricted use of this species in phytoremediation strategies.

Energy saving and quality preservation through modulating time related conditions during interval drying of pumpkin (Cucurbita maxima)

The present study investigated the Interval Starting Accessibility Drying (ISAD) process with the main objective to optimize the main processing parameters, i.e. the active time (tON) and the tempering time (tOFF), which ranged between 5 to 30 s and 1 to 3 min, respectively. ISAD performances were compared with continuous airflow drying for several quality parameters and energy consumption. The modulation of the time related operating conditions allowed rewetting the surface after each tempering time in a total way with tON= 5s-and tOFF=2 or 3min. ISAD significantly affected (p<0.05) the effective drying time and the energy saving which reached as much as 87.26% compared to continuous drying when tON= 5s and tOFF =3 min. The processes did not significantly impact the shrinkage, rehydration capacity or total color change. However, drying processes notably influenced the content of polyphenols and carotenoids. The optimal conditions of combined optimized responses were tON = 5 s of tOFF = 2.52 min with a desirability D= 0.924.

Elutriation of fine particles in a pulsed fluidized bed

This paper reported on fine particle elutriation for two different static bed heights of 25 cm and 30 cm in a pulsed fluidized bed. The effects of three types of flow including continuous airflow, on-off pulsed airflow, and pulsed airflow imposed on continuous airflow were investigated. Observations showed that the elutriation fraction extremely increased with gas temporal average velocity and static bed height for continuous airflow, while for pulsed and mixed flows at the same condition the increase was not considerable. The effect of pulse frequency from 0.033 Hz to 0.1 Hz as an optimum range led to an extreme reduction loss of particles for pulsed and mixed airflows compared to continuous airflow even at high gas temporal average velocities. The elutriation rate of mixed airflow at 0.033 Hz and 3Umf for 30 cm static bed height on average was 75% and 35.3% less than continuous and pulsed airflows, respectively.

Continuous operating elastocaloric air-cooling device

&lt;p&gt;Elastocaloric cooling has shown significant potential as an alternative to traditional vapor-compression technology because it relies on nonflammable, non-toxic, and zero-global warming potential solid refrigerants (usually NiTi and TiNi-based shape memory alloys). However, the uniaxial loading mode commonly used in existing elastocaloric cooling devices is often accompanied by a lower operating frequency. Additionally, using water as the heat exchange medium presents challenges in further cooling the air with cold water. These issues will hinder the application of this type of refrigerators in space cooling scenarios. Here, we report a continuous operating tension-based elastocaloric air-cooling device that utilizes the bundles of NiTi wires. The driving mode based on the cam structure realizes the alternating loading-unloading cycle of multiple NiTi bundles, facilitating continuous the cooling process. Our air-cooling device achieves a temperature decrease of 4.4 �� in continuous air flow and provides a cooling power of 21 W. These results demonstrate the possibility of applying elastocaloric technology in space cooling and provide a technical reference for designing household air conditioners using this technology.&lt;/p&gt;

Air Purification Study Based on the Adhesion Effect between Low-Curvature Liquid Surfaces and Air Convection Friction

Rapid urbanization and industrialization have heightened concerns about air quality worldwide. Conventional air purification methods, reliant on chemicals or energy-intensive processes, fall short in open spaces and in combating emerging pollutants. Addressing these limitations, this study presents a novel water-film air purification prototype leveraging the adhesion between low-curvature liquid surfaces and air convection friction. Uniquely designed, this prototype effectively targets toxic gases (e.g., formaldehyde, SO2, NO2) and particulate matter (such as PM2.5) while allowing continuous airflow. This research explores the adhesion and sedimentation capabilities of a low-curvature water solution surface under convection friction, reducing the surface energy to remove airborne pollutants efficiently. The prototype was able to reduce the initial concentration in a 30 m³ chamber within 180 min by 91% for formaldehyde, 78% for nitrogen dioxide (NO2), 99% for sulfur dioxide (SO2), and 96% for PM2.5. Experimentally validated indicators—decay constants, CADR, and purification efficiency—enable a comprehensive evaluation of the purification device, demonstrating its efficacy in mitigating air pollution. This innovative design, which is cost-effective due to its use of easily accessible components and water as the primary medium, indicates strong potential for large-scale deployment. This study points to an environmentally friendly and economical approach to air purification, shedding light on a promising direction for enhancing indoor air quality. Further optimization and exploration of diverse pollutants and environmental conditions will propel the practical applications of this pioneering technology.

Food waste leachate valorization for sustainable biomass production from Arthrospira maxima

AbstractArthrospira has the ability to tolerate effluents from domestic to farm wastewater. Food leachate coming from fruits and vegetables can be toxic in water discharge due to high dissolved oxygen and nutrient demands. Thus, pretreatment is required before passing through wastewater treatment plants, which generates higher costs and contamination in water bodies. In this work, leachate from fruits and vegetables was used in different percentages to produce Arthrospira maxima using airlift‐type bioreactors with continuous air flow, two photoperiods, and two inoculums. The treatment with 3% leachate (T1) reached 5.23 g/L after 16 days, while the control reached 3.81 g/L (T0). An optimization of the biomass production was carried out seeking to use the maximum percentage of the leachate, resulting in the best treatment of 9% of leachate (T8) achieving 4.88 g/L. After optimization, three cell disruption methods were applied to the obtained biomass, quantifying amino acids and hydrolysis grade (GH), being the ultrasonication treatment the most important reaching 80% GH and a concentration of 25 mg/g of amino acids, while the unbroken biomass contain 13 mg/g. The Arthrospira maxima species is an algae that can be widely used as a bioremediation method, since it managed to reduce the concentrations of COD and orthophosphates, in addition to containing some of the nutrients that plants require for their development, given that plants require amino acids. During its growth, it is proposed to apply the biomass generated from leachates as a plant biostimulant.

Gas-solid two-phase flow triboelectric generator for powder triboelectrification energy collection and road early warning

With the rapid development of modern industrial processes, electrostatic safety issues caused by powder in production and daily life have attracted people's attention. Since powder is small in size and easily agglomerates, it is difficult to observe or design devices to monitor the electrostatic process generated by powder. Herein, a continuous gas-solid two-phase flow triboelectric nanogenerator (GS-TENG) was developed to harvest triboelectricity from the collision process between the powder-air flow and the solid surface. Compared with the signals under non-continuous airflow, the short-circuit current and output voltage signals generated under continuous airflow impact exhibit an unidirectional direct current peak characteristic. Additionally, in order to analyze the relationship between motion of powder airflow and the triboelectric signals, the two-phase flow more comprehensively, a high-speed camera was used to record motion during the charge generation process. Results showed that 3 mm nylon sphere generated normal alternating current signals upon contact and separation from PTFE, while nylon power with the diameter of about 30 µm produced direct current triboelectric signals owing to the effect of point discharge. At a wind speed of 32 m/s, 5 cm distance, 90° impact angle, the short-circuit current and output voltage can reach the maximum values of 20 µA and 130 V, respectively, which can serve as a power source sufficient to power 63 commercial LEDs. Based on the gas-solid two-phase flow triboelectric nanogenerator, a self-powered road warning lights was designed, indicating application prospects in dusty weather.

Effect of swirl-spray impact on the comprehensive performance of uniflow-scavenging opposed-piston engines

Uniflow-scavenging opposed-piston (USOP) engines exhibit high thermal efficiency and power density. However, the USOP engine has a continuous in-cylinder airflow state between different cycles, which affects direct injection oil spray distribution. The USOP engine nozzles were mounted on a cylinder liner. The forward and reverse impacts of the in-cylinder swirl differed in the asymmetric orifice layout. A dual-intake channel USOP simulation model was established. The key parameters of the simulation model were verified, and the effects of forward and reverse impacts under different nozzle layouts and swirl strengths were analysed by simulation. The results show that all swirl-spray impacts benefit the combustion. Swirl-spray impacts can effectively improve the oil spray distribution and atomisation. In addition, reducing the swirl in the next cycle concentrates the exhaust gas in the cylinder centre, improving the scavenging efficiency. Forward and reverse impacts enhance and weaken the in-cylinder swirl, respectively. However, the effect of the reverse impact was more pronounced than that of the forward impact.

SNAP: Implementation of Supportive Non-Invasive Ventilation for Acute Chest Syndrome Prevention in Adults with Sickle Cell Disease

Introduction Acute chest syndrome (ACS) is the 2 nd most common cause of hospitalization and a major cause of mortality in sickle cell disease (SCD). ACS commonly occurs during a hospitalization for a vaso-occlusive crisis (VOC) when the combination of chest wall pain and intravenous opioids may lead to hypoventilation and atelectasis. Incentive spirometry may prevent ACS by encouraging patients to take deep breaths to reduce atelectasis and improve oxygenation, but requires active participation by an awake patient. Non-invasive bi-level positive airway pressure [BiPAP] provides positive pressure breaths via a mask to improve ventilation and prevent atelectasis during sleep. Hospitalized pediatric SCD patients who were at risk for ACS have used nocturnal BiPAP for ACS prevention on the Boston Medical Center (BMC) general pediatric unit since February 2017. In January 2023, BMC instituted the use of nocturnal BiPAP in hospitalized adult patients with SCD who are at high risk for ACS. Methods This is a prospective observational cohort study to examine the safety, acceptability, and tolerability of BiPAP in high-risk adult patients with SCD hospitalized with a VOC. Criteria for increased ACS risk included: 1) Oxygen saturation &amp;lt; 94% on room air at presentation; 2) History of pulmonary hypertension diagnosed by right heart catheterization; 3) Known obstructive sleep apnea (OSA) not currently treated with positive airway pressure; 4) Prior severe ACS requiring invasive or non-invasive ventilation, high-flow oxygen, and/or exchange transfusion; or 5) History of fat emboli syndrome. Exclusion criteria were: 1) OSA being treated with outpatient positive airway pressure, 2) Surgery within the last 30 days, 3) Direct admission to the intensive care unit (ICU). Manual chart extraction was used to collect patient demographic data, medical history, symptoms, vital signs, chest radiography, laboratory data, indications for BiPAP use, and acceptability and use of BiPAP. Results BiPAP was offered during 38 hospitalizations to 25 individual patients (14 (56%) female) between February and July 2023. The mean age was 35.8 years (SD 10.2); 16 (64%) were HbSS, 8 (32%) HbSC and 1 (4%) HbS-β 0. Nineteen patients (76%) were using &amp;gt;1 SCD-modifying therapy; 16 (64%) reported hydroxyurea use. ACS was present on admission in 7 hospitalizations. Patients agreed to try BiPAP in 22/38 hospitalizations (58%) and BiPAP was used for 1 night in 3 hospitalizations, 2 nights in 3 hospitalizations and more than 2 nights in 7 hospitalizations. In 9/22 hospitalizations, attempts at BiPAP use were unsuccessful. Of the 38 hospitalizations in which BiPAP was offered, 3 patients who did not use BiPAP were transferred to the ICU, 2 for ACS and 1 for ketamine infusion for pain that was refractory to high doses of opioids. Three episodes of ACS developed after admission to the hospital: 2 when BiPAP use had not been attempted and 1 when BiPAP was used for 6 days. Blood transfusions were administered during 7 hospitalizations; 5 of which BiPAP was not used. No deaths occurred during this study period. No adverse events were directly attributable to this novel use of BiPAP for ACS prevention. In the 22 encounters where BiPAP use was attempted, four patients noted difficulties with the continuous airflow and feeling suffocated, one reported lightheadedness. One patient who used BiPAP developed oral pain related to periodontal disease. Conclusion Medically stable, adult hospitalized patients with SCD and VOC were willing to try BiPAP to prevent the development of ACS. In 13/22 (59%) BiPAP was tolerated for &amp;gt;1 one night with no adverse events noted. Future directions include optimizing implementation and studying the efficacy of this intervention.

Microstructure and properties of the GEWZ522K casting magnesium alloy based on the Mg–Gd–Nd–Y–Zn–Zr system

The article discusses the solidification and phase composition of the (wt.%) Mg–4.8Gd–2.1Nd–1.6Y–0.4Zn–0.6Zr (GEWZ522K) casting alloy. It is demonstrated that in the as-cast state, the alloy structure comprises primary zirconium particles, dendrites of the magnesium solid solution (αMg), and eutectic intermetallic phases located between dendritic branches. Following solution heat treatment at t = 530±5 °C, the alloy transitions into a single-phase state and can be significantly strengthened through artificial aging after quenching. It is recommended to apply alloy aging at t = 250 °C for 8–10 h or at t = 200 °C for 15–18 h. This approach leads to the maximum strengthening of the alloy, with the best mechanical properties achieved for the alloy aged at t = 250 °C. Regardless of the aging method used, the ultimate tensile strength (UTS) of the samples surpasses 300 MPa, which significantly exceeds that of commercial casting alloys according to GOST 2856-79. The measured corrosion rate for the GEWZ522K alloy is 7.5±0.4 mm/year, that slightly higher than that for the less alloyed commercial alloy ML10 (approximately 2.5 mm/year) tested under similar conditions. Furthermore, the alloy was subjected to tests for ignition resistance when in contact with air. It was observed that with continuous airflow over the specimen’s surface, ignition centers appear at t = 625 °C due to the breakdown of the oxide film, causing the alloy to nearly completely melt. Therefore, the GEWZ522K alloy can be employed as a high-strength casting alloy. However, during the operation of cast parts, particular attention must be paid to safeguarding the surface of these parts against corrosion.