Effects of Different Types of Interlayers on the Interfacial Reaction Mechanism at the Cu Side of Al/Cu Lap Joints Obtained by Laser Welding/Brazing

The influence of tin foil and Ni coatings on microstructures, mechanical properties, and the interfacial reaction mechanism was investigated during laser welding/brazing of Al/Cu lap joints. In the presence of a Zn-based filler, tin foil as well as Ni coating strengthened the Al/Cu joints. The tin foil only slightly influenced the joint strength. It considerably improved the spreading/wetting ability of the weld filler; however, it weakened the bonding between the seam and the Al base metal. The Ni coating considerably strengthened the Al/Cu lap joints; the highest tensile strength was 171 MPa, which was higher by 15.5% than that of a joint without any interlayer. Microstructure analysis revealed that composite layers of Ni3Zn14–(τ2 Zn–Ni–Al ternary phase)–(α-Zn solid solution)–Al3Ni formed at the fusion zone (FZ)/Cu interface. Based on the inferences about the microstructures at the interfaces, thermodynamic results were calculated to analyze the interfacial reaction mechanism. The diffusion of Cu was limited by the Ni coating and the mutual attraction between the Al and Ni atoms. The microstructure comprised Zn, Ni, and Al, and they replaced the brittle Cu–Zn intermetallic compounds, successfully strengthening the bonding of the FZ/Cu interface.

Surface Coating of Cyclotetramethylenetetranitramine (HMX) Particles and Its Property Investigation

To improve the safety of cyclotetramethylenetetranitramine (HMX) particles, the polymer thermoplastic polyurethane elastomer (TPU) and nitrocellulose (NC) were introduced to coat HMX powder by water-solution suspension method and internal solution method, respectively. Scanning electron microscope (SEM) and X-ray photo-electron spectrometry (XPS) were employed to characterize the HMX samples and the role of NC and TPU in the coating processes were discussed. The impact sensitivity, friction sensitivity, and the thermal decomposition of coated HMX particles were investigated, and compared to the unprocessed ones. The results indicate that both TPU and NC can improve the wetting ability of the coating materials on HMX surface and reinforce the connection between HMX and the coating materials. The impact sensitivity and friction sensitivity of HMX samples decrease obviously after they have been surface coated; the drop height (H50) is increased from 35.24 cm to 50.08 cm, and the friction probability is reduced from 93.2 % to 58.3%. The activation energy (Ea) and the self-ignition temperature increase by 10.46 KJ·mol-1 and 1.8, respectively.

Labortory and Pilot Tests of Enhanced Oil Recovery through Wettability Alteration by Diluted Microemulsions

Replacing oil from small pores of tight oil-wet rocks relies on altering the rock wettability with the injected fracturing fluid. Among different types of wettability-alteration surfactants, the liquid nanofluid has less adsorption loss during transport in the porous media, and can efficiently alter the rock wettability; meanwhile, it can also maintain a certain oil-water interfacial tension driving the water imbibition. In the previous study, the main properties of a Nonionic nanofluid-diluted microemulsion (DME) were evaluated, and the dispersion coefficient and adsorption rate of DME in tight rock under different conditions were quantified. In this study, to more intuitively show the change of wettability of DME to oil-wet rocks in the process of core flooding experiments and the changes of the water invasion front, CT is used to carry out on-line core flooding experiments, scan and calculate the water saturation in time, and compare it with the pressure drop in this process. Besides, the heterogeneity of rock samples is quantified in this paper. The results show that when the DME is used as the fracturing fluid additive, fingering of the water phase is observed at the beginning of the invasion; compared with brine, the fracturing fluid with DME has deeper invasion depth at the same time; the water invasion front gradually becomes uniform when the DME alters the rock wettability and triggers the imbibition; for tight rocks, DME can enter deeper pores and replace more oil because of its dominance. Finally, the selected nanofluids of DME were tested in two horizontal wells in the field, and their flowback fluids were collected and analyzed. The results show that the average droplet size of the flowback fluids in the wells using DME decreases with production time, and the altered wetting ability gradually returns to the level of the injected fracturing fluid. It can be confirmed that DME can migrate within the tight rock, make the rock surface more water-wet and enhance the imbibition capacity of the fracturing fluid, to reduce the reservoir pressure decline rate and increase production.

Investigation about wetting ability (surface tension) of water used for preparation of pesticide solutions

<p class="042abstractstekst">The investigation about surface tension of water used for preparation of pesticide solutions reveals it is quite diverse and changeable without any logical correlation towards location, time, and type of water source. Moreover, spraying with solutions with lower surface tension give bigger flow rates due to the lower resistance of fluid to the nozzles. The conducted trials show that plant surfaces with more rough texture require to be sprayed with pesticide solutions with lower surface tension. The wax content of the surfaces has no significant impact on surface tension requirement.</p><p> </p>

Optimization of titanium dioxide wetting in alkyd paint and varnish materials in the presence of surfactants

This paper reports the results of studying the influence of surfactants (SAS) on the wetting of titanium dioxide in alkyd paint and varnish materials (PVM), based on pentaphthalic (PPh) and alkyd-urethane (AU) film-forming substances. Edge wetting angle (θ°) and adhesion work (Wa) were used as the criteria for assessing the wettability of titanium dioxide. Three additives were used as SAS: the original product AS-1, obtained from waste of oil refining (with low cost), and industrial additives: "Telaz" and polyethylene polyamine (PEPA). All the studied additives in PPh and AU PVM improve the wetting of titanium dioxide. At the 30 % content of AS film-forming substance in the composition, the maximum decrease in θ° for AS-1 is 4.5°, for PEPA and Telaz it is 4°. For pentaphthalic composition under similar conditions, a decrease in edge wetting angle for AS-1 is 10 °, for Telaz 8.6°, and for PEPA 5.9°. According to the relative change in edge wetting angle for both systems, the maximum decrease in θ° is about 10 %. The introduction of SAS into the composition of AU ambiguously affects the adhesion work, for PPh, the introduction of SAS causes a decrease in adhesion work (Wa). AS-1 is the SAS that minimally reduces adhesion work. The compositions of the PVM by the method of probabilistic-deterministic planning, which ensures maximum wetting of titanium dioxide with film-forming solutions, were analyzed. The equations for calculating the edge angle of wetting of titanium dioxide depending on the content of solvent and the SAS in the PVM were derived. The effectiveness of the AS-1 product as a wetting additive for alkyd paints and varnishes was proven. The wetting ability of the original SAS – AS-1 is close to industrial additives PEPA and Telaz.

Comparative studies on the durability and moisture performance of wood modified with cyclic N-methylol and N-methyl compounds

Glyoxal-based condensation resins like 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) have been used to modify wood and improve its resistance against decaying fungi. High biological durability of DMDHEU-treated wood has already been confirmed in laboratory and field tests in the past. However, the modes of protective action behind an improved decay resistance are not fully understood yet. Furthermore, it is questionable how the use of formaldehyde-poor N-methylol and formaldehyde-free N-methyl compounds instead of DMDHEU affects the moisture behavior and durability, respectively. In this study, wood blocks were treated with N-methylol (DMDHEU, methylated DMDHEU) and N-methyl compounds (1,3-dimethyl-4,5-dihydroxyethyleneurea; DMeDHEU). Untreated and modified specimens were exposed to different moisture regimes and wood-destroying fungi in order to study the indicators that control changes in the wetting ability and decay resistance. Both N-methylol and N-methyl compounds decreased the water uptake and release and increased the durability of Scots pine sapwood from ‘not durable’ (DC 5) to ‘very durable to durable’ (DC 1–2). However, high fluctuations were observed in water uptake and release as well as mass loss (ML) caused by fungal decay, when modified specimens were tested without passing through a cold-water leaching. Consequently, a significant effect of the leaching procedure according to EN 84 on the durability classification could be established. The latter appeared more pronounced for treatments with N-methyl compounds compared to N-methylol compounds. Finally, wetting ability (kwa) and resistance indicating factors (kinh) enabled a forecast of high biological durability for both treatments with N-methylol and N-methyl compounds under real service life conditions.

Detergent properties of aqueous extract of Aatreelal (Ammi majus L.) and Babchi (Psoralea corylifolia L.)

Aim of the study: To evaluate the detergent activity of aqueous extract of Ammi majus L. and Psoralea corylifolia L. Materials and methods: The detergent activity of aqueous extract of test drugs was evaluated by using a standard physicochemical test with Sodium lauryl sulfate (SLS) as a standard drug. Surface tension was measured by Du Nouytensiometer; Dirt dispersion by using Indian ink; Cleaning ability by greasy wool yarn test; Foaming properties by cylinder shake method and Wetting ability by canvas disc method. pH values and total saponin was also determined. Both the test and standard drugs were analyzed in 1% and 5% concentrations. Results: The aqueous extract of both the test drugs produced a significant detergent effect at both the concentration but less than SLS as it exhibited a pronounced effect in all the parameters except detergency. The test drugs were found to be acidly balanced; exhibited a prominent surface tension reduction, high foaming, wetting, and cleaning ability with a good quantity of saponin. Conclusions: Based on the above results it can be concluded that the aqueous extract of test drugs has significant surface-active properties thus these drugs can be used as a natural surfactant.

Static wetting angles of water and sulphur at the zinc sulphide surface modified with anionic surfactants and their combinations

This paper looks at the effect produced by surface modification of the super pure zinc sulphide monocrystals with certain surfactants and their combinations (sodium lignosulphonate (SLS), sodium dodecyl sulphate (SDS), sodium dodecylbenzenesulphonate (SDBS) and the following combinations: SLS + SDS, SLS + SDBS on the surface angle of wetting with water and elemental sulphur melt. It was found that as the concentration of individual surfactants in the solution rose, so did the wetting ability of the mineral surface. Thus, at the surfactant concentration of 0.8 g/dm3 the water wetting angle reaches 48.4o for SLS, 22.5o for SDS and 10.3o for SDBS; the elemental sulphur wetting angle is 71.3o for SLS, 76.9o for SDS and 67.9o for SDBS. The work of adhesion in the system ZnS – Surfactant – Н2О increases by 9–11%, and in the system ZnS – Surfactant – S0 — by 5–8%. When using the combinations SLS + SDS (СSLS = 0.2–0.8 g/dm3) and SLS + SDBS (СSLS = 0.2 g/dm3), inverse surface wetting of zinc sulphide with elemental sulphur melt is observed. The maximum wetting angles reached are 93o and 85o, correspondingly. The work of adhesion and the spreading coefficient expectedly decrease. The paper analyzes the effect of individual surfactants and their combinations on the pressure leaching of zinc sulphide concentrate. The use of individual surfactants intensifies the transition of valuable components into the solution. The biggest increase in recovery was seen when using SLS, and namely 27–32% for zinc and 11–16% for copper. The recovery of zinc increased by 31–41% in the presence of SLS + SDS and by 27–34% in the presence of SLS + SDBS. This research was funded by the Russian Science Foundation, Grant No. 18-19-00186.