Abstract Aluminum Research Articles

New Emerging Al7075 Based Hybrid Nanocomposite for Automotive Applications: A Sustainability Approach

Aluminium matrix composites (AMCs) have emerged as the substitute for the monolithic (unreinforced) materials over the past few decades. The applications of AMCs are common in automotive, aerospace, defence and biomedical sectors due to its lower weight, high strength, high resistance against corrosion and high thermal and electrical conductivity. In this work, it is aimed fabricate a new class Al 7075 based hybrid composites reinforcing with nanoparticulates suitable for automotive application. Al7075 reinforced with fixed quantity of boron carbide (B4C) (1.5 wt.%) and varying wt % of flyash (0.5 wt.%, 1.0 wt.%, 1.5 wt.%) is fabricated using ultrasonic-assisted stir casting technique. Physical and mechanical characterization such as density, porosity, micro hardness, tensile strength and impact strength were estimated for three different compositions. The tensile strength and percentage increase in hardness value of the nanocomposite Al7075-B4C (1.5 wt. %)-flyash (0.5 wt. %): HNC3 found maximum as 294 MPa and 32.93%. In comparison with Al7075 alloy the impact strength of HNC3 shows the highest percentage of 9.31% respectively.

Fabrication of Al Alloy-Based Metal Matrix Composites and Use the Interpolation Approach for Mechanical Properties Estimation

Aluminum alloy-based metal matrix composites (AMMCs) are extensively utilized due to their distinctive mechanical properties. Al-6%Si alloy was reinforced with different contents of alumina (Al2O3) particles (0, 1.5, 3, 4.5, 6, 7.5, 9, 10.5 and 12% wt.) and the MMCs were prepared by stir casting at 800°C. Microstructural characterization of AMMCs was studied using optical microscopy, to emphasize the homogeneous distribution of the reinforcement particles (Al2O3) in the Al alloy matrix. Hardness and wear tests were used to study the influence of Al2O3 addition on the mechanical properties of the prepared composites. The interpolation method is applied as a perfect alternative approach for saving the consumed time during the experimental work. The used mathematical expression can be utilized for an early prediction of the mechanical properties of AMMCs at different contents of Al2O3 particles without carrying out much experimental analysis. The current study shows that the linear interpolator is the optimal one where it achieved Mean square error (MSE) equals 0.1875, and 0.0119 for hardness and wear loss tests, respectively.

Microstructure and alloy element distribution near the fusion line of aluminum alloy 6061 in laser wire-filling welding

Aluminum alloy 6061(AA6061) sheets of 4 mm in thickness are joined by laser wire-filling welding (LWFW) using the ER4047 welding wire. Microstructure and alloy element distributions near the fusion line are characterized and are investigated by optical microscope, scanning electron microscope, energy dispersive spectrometer. The results showed that the well-formed welded joints are obtained with a few thermal cracks near the fusion line. The coarse grain and a reduction in the weight ratio of magnesium to silicon can be observed, when the welding speed decreases under constant laser power. The thermal crack is caused by the decrease of the weight fraction of magnesium and the proportion of silicon content has an effect on the microhardness of welded joints. By properly controlling the welding speed, the various properties of AA6061 LWFW joints can be balanced.

Macrophagic myofasciitis and subcutaneous pseudolymphoma caused by aluminium adjuvants

Aluminium hydroxide is a well-known adjuvant used in vaccines. Although it can enhance an adaptive immune response to a co-administered antigen, it causes adverse effects, including macrophagic myofasciitis (MMF), subcutaneous pseudolymphoma, and drug hypersensitivity. The object of this study is to demonstrate pediatric cases of aluminium hydroxide-induced diseases focusing on its rarity, under-recognition, and distinctive pathology. Seven child patients with biopsy-proven MMF were retrieved from the Seoul National University Hospital (SNUH) pathology archives from 2015 to 2019. The medical records and immunisation history were reviewed, and a full pathological muscle examination was carried out. The mean age was 1.7 years (8.9–40 months), who had records of vaccination against hepatitis B, hepatitis A, and tetanus toxoid on the quadriceps muscle. The chief complaints were muscle weakness (n = 6), delayed motor milestones (n = 6), instability, dysarthria, and involuntary movement (n = 1), swallowing difficulty (n = 1), high myopia (n = 1), and palpable subcutaneous nodules with skin papules (n = 1). Muscle biopsy showed MMF (n = 6) and pseudolymphoma (n = 1) with pathognomic basophilic large macrophage infiltration, which had distinctive spiculated inclusions on electron microscopy. The intracytoplasmic aluminium was positive for PAS and Morin stains. Distinctive pathology and ultrastructure suggested an association with aluminium hydroxide-containing vaccines. To avoid misdiagnosis and mistreatment, we must further investigate this uncommon condition, and pharmaceutical companies should attempt to formulate better adjuvants that do not cause such adverse effects.

Physiological and Growth Response of Sweet Corn Hybrids to Aluminum-Induced Stress

Aluminum (Al) stress has strong negative effects on growth, development and yield formation in crops. However, few studies focused on aluminum stress in sweet corn seedlings. In the present study, 18 sweet corn varieties were used to analyze the morphological and physiological changes of sweet corn seedlings in response to Al-induced stress. Results have shown that treatment by AlCl3, significantly affected root elongation, chlorophyll content, plant height, fresh weight, superoxide dismutase (SOD) activity, peroxidase (POD) activity, catalase (CAT) activity and Al content in root tips in sweet corn, according to the significant interaction by variety × AlCl3 treatment except for CAT. Al-induced stress inhibited root length in all sweet corn varieties, and it resulted in a decrease in chlorophyll content, plant height, fresh weight, and SOD activity in most of the sweet corn varieties. The treatment by AlCl3 increased in POD activity except for GLT31; however, the intensity of these effects varied among varieties. In addition, the correlation between morphological and physiological characteristics showed that Al content in root tips was negatively correlated with relative root growth (RRG) and chlorophyll content at a significant level of 0.01, and it was negatively correlated with CAT activity at the significant level of 0.05. There were significant positive correlations between plant height and fresh weight at a significant level of 0.01, and chlorophyll content was positively correlated with RRG and CAT at the significant level of 0.05. The principal component analysis showed that plant height, RRG, SOD activity, fresh weight, Al content of root tips and fresh weight were the main morphological and physiological characteristics in sweet corn seedlings affected by AlCl3 treatment. In addition, we found that HWT2, HWT1 and HZ388 were the high-tolerant varieties to Al treatment.

Effect of the Ceramic Burning Temperature on the Characteristics of the Emission Spectrum (LIBS) of Al and Transmittance (FTIR) of Al-O on Ceramic Body of BL-1 Type

Aluminum (Al) contained in materials such as clay, kaolin is one of the elements that play an important role in the ceramic body. Al binds to other atoms like Si (quartz) to form a ceramic frame that is strong and not easily cracked. In addition, the bond with the group -OH plays an important role in relation to the ability of ceramics to absorb water. In this study, BL-1 type ceramic samples have been made with five variations of the burning temperature between 800-1000oC. To determine changes in the Al atomic content of ceramic samples were characterized by LIBS and FTIR spectrophotometers. The results of LIBS characterization of all samples showed two bands with peaks at wavelengths of 394.4 nm (Al-I) and 396.6 nm (Al-II) which are the characteristic peaks of Al atoms. The peaks with the highest intensity of Al-I and Al-II were resulted by samples that were burned at 900oC. Meanwhile, the results of FTIR characterization have shown a spectrum with bands at wavenumbers between 1030-1060 and 1150 cm-1 which are characteristic bands of stretching vibrations from Al-O. The peak of the band in the wavenumber between 1030-1060 cm-1 shifts towards a larger wavenumber with increasing the burning temperature.

Effect of Nano-Al<sub>2</sub>O<sub>3</sub> on Characteristics of Aluminium A356 Matrix Composite Produced by Stir Casting Route

Aluminium Matrix Composites (AMCs) made by A356 as matrix and nanoAl2O3 as reinforced are widely used for high performance application because of light weight and alumina has good performance at high temperature. In this study, the nanoAl2O3 used varied from 0.1 vf-% to 1.2 vf-%, which subsequently determined the optimum point. In addition, the magnesium with 10% are added as a wetting agent between aluminium and nanoAl2O3 as reinforced. Stir casting process is carried out for 2 minutes and 4 minutes for the degassing process using argon gasses then pouring molten metal in to the mold at 800°C. The effect of nanoAl2O3 on the mechanical properties and microstructure of the composites was investigated. The result showed that the tensile strength decreased with the addition of nanoAl2O3 but the hardness increased. Increasing of hardness mainly caused by grain refinement, and particle strengthening which act as obstacles to the motion of dislocations. Addition of nanoAl2O3 as reinforced also tend to form microporosity and agglomeration which would decrease the tensile strength of composites. The optimum strength was reached by 0.5 %Vf nanoAl2O3 with the value of 140 MPa and hardness of 46 BHN which was supported by low porosity level. Keyword : Al A356, Al2O3, nanoComposite, Stir Casting

Uji ketahanan fatik aluminium hasil remelting piston bekas menggunakan metode pengecoran centrifugal casting

Aluminum is one of the non-ferrous metals that are most widely used in the engineering field due to it has mild properties and is resistant to corrosion, but aluminum waste such as used pistons that are damaged or not utilized as an proper resource, on the other hand, that this process is very potential due to it uses a used piston that is not used, and is expected to have a better economic value by doing remelting and centrifugal casting to the used piston. This study aims to determine the value of the fatigue cycle of the used piston which is remelting and printed using the centrifugal casting method by using variations in the pouring temperature and die temperature and rotation variations. Based on the tests conducted using pouring temperature variations and rotation speed are as follows: best cycle value at 250 rpm variation is at pouring temperature 600oC with a value of 76000 N, and the lowest is at room temperature of 750oC with a value of 32000 N, best cycle at a variation of 500 rpm is at a pouring temperature of 700oC with a value of 40000 N, and the lowest is at a room temperature of 660oC with a value of 12000 N. The best cycle value at a variation of 750 rpm is at a pouring temperature of 750oC with a value of 16000 N, and the lowest is at room temperature 660oC with a value of 10000 N. While the results of subsequent tests conducted using variations in die temperature and rotation speed are as follows: the best cycle value at 250 rpm variation is at a print temperature of 350oC with a value of 17400 N, and the lowest is at room temperature of 250oC with a value of 8370 N. The best cycle value at a variation of 500 rpm is at a print temperature of 350oC with a value of 67760 N, and the lowest is at a room temperature of 250oC with a value of 22850 N. The best cycle value at a variation of 750 rpm is at a print temperature of 350oC with a value of 75170oC. and the lowest is at room temperature of 250oC with a value of 28940 N.Keywords: Centrifugal casting, fatigue test, remelting, used piston, aluminum, cycle value.

Transcriptome analysis of Cryptococcus humicola under aluminum stress revealed the potential role of the cell wall in aluminum tolerance.

Aluminum (Al) toxicity is one of the most important limiting factors for crop yield in acidic soils. Bound Al gets converted into a toxic ionic state (Al3+) in acidic soil. Recent studies have shown that Al can act on the cell walls, cell membranes, organelles, and nuclei of microorganisms and affect substance and energy metabolism. To explore the gene expression at the transcriptional level under Al stress, we sequenced the transcriptome of Cryptococcus humicola, which is a highly Al-resistant yeast strain isolated from acidic soil and tolerates up to 200 mM Al3+. The screening conditions for genes from the control and experimental group were a false discovery rate (FDR) <0.05 and log 2|FC| > 1. A total of 4760 genes were differentially expressed, among which 3066 were upregulated and 1694 were downregulated. These genes control glycometabolism, protein synthesis, lipid metabolism and signalling pathways. Eleven selected differentially expressed genes were further validated using qRT-PCR. The results suggested that Al stress leads to complex responses in C. humicola. The effects of Al on the β-d-glucan and mannose contents and Al accumulation in the cell wall were determined. With an increase in the Al treatment time and concentration, the contents of β-d-glucan and mannose showed a trend of first increasing and then decreasing. Under Al treatment, the Al content of the cell wall also showed a trend of first increasing and then decreasing. These results suggested that Al accumulates in the cell wall and the cell wall plays a vital role in the Al resistance of C. humicola. The differentially expressed genes provide a foundation for the further study of Al tolerance in C. humicola.

Characterizations of Cladded 6082-T6 Aluminum Alloy Through Hard Anodizing

Aluminum alloys have attractions to be used for a wide range of applications. Although the passive film on aluminum can provide corrosion protection, it has limited wear resistance in oil and gas applications due to the aggressive environment. This work has investigated the enhancements of hard anodizing on the performance of 6082-T6 aluminum alloy surface against erosion and corrosion test environments. The study investigates the surface roughness and hardness of the hard-anodized coating before going deeper in the cross-section to study in details the macro/microstructure of the formed layer. The erosion resistance of the coated layer, in particular, the effect of sand concentration and temperature variations to the aqueous slurry impingement against material properties such as adhesion, ductility, and roughness were investigated. In addition, a series of electrochemistry tests have been conducted to verify the corrosion performance. As a reference, the un-coated aluminum substrate was instigated in all the experiments. The resulted hard anodized coating layer had good adhesion with the aluminum substrate and was consisted of two distinct amorphous sub-layers of almost 50 m thick with some elongated porosity. It has been shown that the erosion resistance of aluminum alloy can be highly improved by hard anodizing, especially at high temperature. The hard-anodized sample shows almost twice hardness values compared with aluminum substrate for both eroded and un-eroded conditions. For the corrosion behavior, the hard-anodizing coating has lower corrosion current density than the aluminum substrate.

Effect of Al on the growth and nutrients uptake of blueberries (Vaccinium spp.)

Aluminum (Al) is the major factor limiting plant growth on acidic soils. Blueberry (Vaccinum spp.) is an acidophilic plant. Highbush blueberry and rabbiteye blueberry are the main commercially cultivated species, while the response of which to Al is still unclear. Therefore, hydroponic experiments were conducted to determine the effect of Al (0 and 100 μmol L−1) on the growth and nutrient uptake of highbush blueberry ‘Brigitta’ and rabbiteye blueberry ‘Brightwell’. The results showed that root biomass, root length per fresh weight, root activity and foliar nitrogen (N) concentration of ‘Brigitta’ were significantly decreased by Al, while root lipid peroxidation was increased by Al. In contrast, the biomass and root activity of ‘Brightwell’ were not affected by Al treatment, root lipid peroxidation was significantly decreased, root length and surface area per fresh weight were increased compared with the control, which was benefic for nutrients absorption. In fact, foliar N concentration of ‘Brightwell’ was increased in Al treatments. However, fewer Al was accumulated in leaves of ‘Brightwell’ compared to ‘Brigitta’. Therefore, it could be concluded that growth and nutrients uptake of ‘Brightwell’ was not negative affected by Al, which meant ‘Brightwell’ was resistant to Al, compared to ‘Brigitta’.

Ultrahigh Gain of a Vacuum-Ultraviolet Photodetector Based on a Heterojunction Structure of AlN Nanowires and NiO Quantum Dots

Aluminum nitride ($\mathrm{Al}\mathrm{N}$) is a promising candidate for the manufacture of vacuum ultraviolet (VUV) photodetectors. However, its poor electrical conductivity limits its applications. Herein, a high-performance $\mathrm{Al}\mathrm{N}$ nanowire (NW)-$\mathrm{Ni}\mathrm{O}$ quantum dot (QD) based VUV photodetector is constructed via a mixed-dimensional strategy. The formation of isolated nanoscale p-n heterojunctions greatly increases the concentration of photogenerated electrons, resulting in an ultrahigh photoconductive gain (9.96) in the $\mathrm{Al}\mathrm{N}$ NW-$\mathrm{Ni}\mathrm{O}$ QD material, which is about 27-fold higher than that of $\mathrm{Al}\mathrm{N}$ NW (0.368). In addition, the significant improvement in both photocurrent and response speed convincingly suggest the great potential of $\mathrm{Al}\mathrm{N}$ NW-$\mathrm{Ni}\mathrm{O}$ QD based VUV photodetectors. Furthermore, the properties of these photodetectors in an irradiation environment are also evaluated here. It is found that $\mathrm{Al}\mathrm{N}$ NW exhibits excellent anti-irradiation characteristics towards both electron and proton irradiation, while the $\mathrm{Al}\mathrm{N}$ NW-$\mathrm{Ni}\mathrm{O}$ QD material also presents promising potential under low-dose electron irradiation. This study can be used as a guideline to design and fabricate high-performance VUV photodetectors based on wide-band-gap semiconductors coupled with other nanostructured systems.

Friction Stir Welding of Aluminum Sponge by Non-Porous Edge Retention

Aluminum sponge is obtained by gravity die casting technique using altruist die and silica sand space holders. Development of appropriate welding techniques for these metals is needed for their extensive utilization in various industries such as automobile, aerospace, and ship building. In this work, feasibilities and limitation of casted macro-porous aluminum sponge welding are analyzed. Considering the intractability in accomplishing welding by friction stir welding, the authors’ own aluminum sponge is produced by gravity die casting with the aid of altruist polymer die. Current casting methods followed by other manufacturers involve aid of high-pressure infiltrator and vacuum chamber to produce aluminum sponge. In this novel technique of producing aluminum sponge, neither vacuum assistance nor high-pressure infiltrator was needed, thereby reducing overall operating cost. Friction stir welding was performed on aluminum sponge of 8 mm thickness with cylindrical tool of shoulder diameter 25 mm and pin length 5.8 mm, tool material being high speed steel. A novel method of non-porous edge retention was considered for welding aluminum sponge to retain cellular integrity. The weld joints obtained at three different tool rotations speed of 600 rpm, 800 rpm and 1000 rpm were examined visually and with X-ray images along with few tests to determine mechanical strength. The weld joints obtained at higher speeds were free from defects, and tensile strength was few times higher to that of tensile strength of other commercially available sponge. Aluminum sponge welding by FSW

Control and Mechanism Analysis of Serrated Chip Formation in High Speed Machining of Aluminum Alloy 7050-T7451

Aluminum alloy 7050-T7451 is widely used in aeronautical large structural parts, and high speed cutting is often used in machining. The serrated chip is a critical state for chip formation in high speed cutting, and its formation and control mechanism are of great significance for actual machining. To study the chip formation of high speed cutting aluminum alloy 7050-T7451, the chips at different cutting speeds are obtained by high speed cutting experiments. Combined with microscopic observation, the chip shape evolution, chip localization fracture process and mechanism of different cutting speeds are analyzed. The morphological evolution of chips and the mechanism of chip breaking during high speed cutting of aluminum alloy are revealed. According to the machined surface of the chip root and the angle of the chip, the formation mechanism of the curl radius formed by the chip is analyzed. The critical cutting speed of plastic-brittle transformation of aluminum alloy 7050-T7451 in high speed cutting is obtained by studying the critical condition for strip-to-serration transition of chip morphology.

Effect of Time Voltage and Voltage of 1100 Aluminum Coating Using Chitosan Using Electrodeposition Method

Aluminum has mechanical properties such as light, easy to form, and the ability to conduct heat and electricity, but has less corrosion resistance properties. One effort to improve corrosion resistance in aluminum is by electrodeposition method. The electrodeposition process was carried out with a variation of time 10, 20, and 30 minutes and variations in voltage of 5 V, 10 V, and 15 V using AA 1100. The electrolyte used was a mixture of acetic acid and chitosan. Coating thickness measurement was carried out using NOVOTEST TP-1M coating thickness gauge, the corrosion rate was measured with 128N Autolab PGSTAT Potentiodynamic and surface roughness measurements using Mitutoyo SJ-210 Surface Roughness Tester. Based on the research data, it was found that the results of optimum layer thickness were obtained at 10 Volt variation of 20 minutes at 11 μm ± 0.04%. Specimens without treatment had the highest corrosion rate of 0.25541 mpy while the lowest corrosion rate was in the 10 variations of 20 minutes which produced 0.0078935 mpy. The surface roughness data of the specimen without treatment was 1.034 μm. The results of the smallest surface roughness were obtained at 10 V 20 minutes variation of 0.725 μm, while the largest surface roughness results in a variation of 15 V 30 minutes which was 2.529 μm. In this stud, it is known that the higher the time and stress used in the electrodeposition process results in greater corrosion rates, because it produces a higher layer thickness but results in higher surface roughness as well.

Transition Between Severe and Mild Wear of 2024A-T4 Anodized Aluminum Alloy under Severe Wear Conditions

Aluminium alloys are gradually replacing grey cast iron in the automotive industry thanks to its low density. The purpose of this study is to evaluate tribological properties of 2024A anodized aluminium alloy under severe wear conditions. For this aim we are investigating the effect of the sliding speed and the anodic layer in order to improve the wear resistance and friction properties of 2024A aluminium alloy and this by using the latter with the hard metal chrome steel 100C6 in dry punctual contact. So we shall evaluate hardness, wear rate and friction properties after and before the anodizing process. The results have shown that the sliding speed affects a transition from severe wear to mild wear when u = 0.3 m/s for the alloy covered by hard anodic layer, as well as it was a significant decrease in wear rate.

Fabrication and characterization of Al/glass zig-zag thin film, comparing to the discrete dipole approximation results

Aluminum zig-zag thin film was coated on the glass substrate by the oblique angle deposition (OAD) method. X-ray diffraction (XRD) revealed the formation of cubic phase with the peak in the (111) plane. The field emission scanning electron microscopy (FESEM) analysis used to estimate the films thickness, columns magnitude and its shape. The unpolarized light absorption spectrum of the zig-zag Al thin film was obtained by spectroscopy analysis in 330–850 nm. Besides, the scattering and absorption spectra of these nanostructures were simulated by the discrete dipole approximation (DDA) and the results compared to the empirical data. The Al zig-zag thin film was simulated by an array of electric dipoles and optical spectra were obtained as function of azimuthal angles and arm lengths. The simulation results show that, at the zero degree incident angles for different azimuthal angles the peaks intensity increases by decreasing azimuthal angle. Besides, by increasing the arm lengths, the peak of shorter wavelength shifts toward the longer wavelengths and the peak of longer wavelength become sharper. From a general viewpoint, the observations had a good agreement to empirical data, nevertheless, the differences needs special attention.

Tolerance of Douglas Fir Somatic Plantlets to Aluminum Stress: Biological, Cytological, and Mineral Studies.

Aluminum (Al) is well known as a potent inhibitor of plant growth and development. It is notably present in soils in the soluble and bioavailable form Al3+ when the soil pH drops below 5. This situation is frequent, especially in softwood forests when litter decomposition is slow. In the present work, we studied the effects of Al3+ on the growth and development of Douglas fir plantlets. Somatic plantlets, regenerated via somatic embryogenesis, were grown in vitro on media supplemented with different concentrations of aluminum chloride (AlCl3): 0 µM, 200 µM, 500 µM. and 1 mM. We show that a concentration of 500 µM AlCl3 in medium significantly reduced root elongation (−21.8%), as well as stem growth (−14.6%). Also, a 25% reduction in dry mass of the plantlets was observed in presence of a concentration of 200 µM of AlCl3. Histological analysis of root tissues revealed significant damage, especially in conducting vessels. In addition, mineral cation content of plantlets was disturbed under Al exposure. More particularly, the Mg and K contents of needles and the Ca content of stems and needles were significantly reduced in presence of a concentration of 500 µM AlCl3 in the culture medium (−35.6%, −33.5%, −24%, and −34% respectively). However, all these damages appeared at relatively high Al concentrations when compared with other herbaceous species. This study shed light on the ability of Douglas fir in vitro plantlets to cope with the acid-driven toxicity of Al.

Occurrence of endogenous hormones in the roots of Masson pine (Pinus massoniana Lamb.) seedlings subjected to aluminum stress under the influence of acid deposition

Aluminum (Al) toxicity is perceived as a potential threat to the integrity of forest ecosystems. The detrimental effects of acidic deposition on trees are caused by mobilization of Al in soils. To better understand how roots adapt to acidic deposition releasing toxic Al including the endogenous hormones {{abscisic acid (ABA), gibberellic acid (GA3), indole-3-acetic acid (IAA) and zeatin riboside (ZR)}}, chemistry {{Ca/Al ratio, and base saturation (BS)}}, and growth rate, with the 100-day-old Masson pine (Pinus massoniana Lamb.) seedlings as research target, we studied the responses of the hormones to rhizospheric Al concentrations and their relationships between pine growth rates and Ca/Al ratios in the simulated soil solutions and forested soils differing in BS. In a hydroponic culture, after the seedlings were exposed to the simulated soil solutions containing 0 (control), 50, 100, 150, 200 µM Al at pH 4.0, ABA formed in the roots increased significantly with the time and intensity of Al exposure. ABA concentrations were positively correlated with rhizospheric Al concentrations (r = 0.92), whereas the opposite trend was seen for GA3 (r = −0.77). Simultaneously, IAA and ZR did not change with the increasing Al concentrations. Increasing of either Al concentration or exposure time caused an inhibition of root elongation and seedling growth. Moreover, in a field soil culture, the seedlings were grown for 60 days (d) in either A horizon soils with a BS above 17% or B horizon soils with a BS below 7%. Evident regional variation of ABA concentrations was observed in the pine roots, which declined in the order: Jin Yun Shan > Nan Shan > Tie Shan Ping, as well as B horizon soil > A horizon soil. Also, ABA concentrations were negatively correlated with soil Ca/Al ratios (r = −0.67). The opposite trends were simultaneously observed for GA3, IAA and ZR (r = 0.45, 0.25 and 0.18, respectively). Based on the laboratory and field results, under the influence of acid deposition, ABA, and GA3 may play an important synergic role in regulating Al resistance of Masson pine as an Al-stress signal.

Effect of Corrosion Protection Method on Properties of RSW and RFSSW Lap Joints Applied in Production of Thin-Walled Aerostructures.

Aluminum structures, and in particular an element of aerostructures, are strongly exposed to the effects of weather conditions. In the case of using new techniques of joining these structural elements, the selection of proper corrosion protection without losing the required properties of the joint may determine its potential application. This paper presents the results of experimental research concerning the influence of corrosion protection on the microstructure and mechanical strength of resistance spot welded (RSW) and refill friction stir spot welded (RFSSW) joints. The tests were carried out on 2024 T3 aluminum alloy, both sides alcladed. For comparison purposes, the following joints were welded: without any protection, with the primer layer, with anodic oxide coating, and with anodic oxide coating plus sealant between the overlapping surface of the welded metal sheet. The samples were visually inspected, and metallographic and mechanical strength examination was conducted. The test results indicate that the application of the protective layers and its type have an impact on the strength of RSW and RFSSW joints. The use of an adhesive or sealant in welded joints provides an increase in the load capacity of the joint.