Addition Of Slurry Research Articles

Mechanisms of Chemically Promoted Material Removal Examined for Molybdenum and Copper CMP in Weakly Alkaline Citrate-Based Slurries

Chemical mechanical planarization (CMP) of metal components is an essential step in the fabrication of integrated circuits. Metal CMP is a complex process where strategically activated (electro)chemical reactions serve to structurally weaken the surface layers of the material being processed, and the resulting overburdens are removed under low-force abrasion. Understanding the tribo-electrochemical mechanisms of this process is crucial to successfully designing the consumable materials for advanced CMP slurries that are needed for the new technology nodes. Using a model CMP system involving copper (wiring material in interconnect structures) and molybdenum (a new diffusion barrier material for copper), the present work illustrates a tribo-electroanalytical scheme for studying various mechanistic details of metal CMP. Electroanalytical probes are employed both in the absence and in the presence of surface polishing to quantify the interplay between mechanical abrasion and chemical surface modification. Weakly alkaline slurry formulations are tested with variable concentrations of silica abrasives and a complexing agent, citric acid. The results serve to examine the link between material removal and tribo-corrosion and to identify the functions of the active slurry additives in governing the rates and selectivity of material removal for CMP.

Synergistic Effects of Magnesium Oxide and SBR Latex Additives on Cement Sheath Stability in Oil Well Operations.

Leaks through cement sheaths remain a complex and challenging issue in the oil industry, representing a persistent obstacle that has endured for decades. The drying shrinkage, an inherent characteristic of Portland cement, substantially exacerbates this problem, driving the formation of microcracks and heightened permeability under variable stress conditions. In this context, additives emerge as significant elements in addressing this issue, offering a pathway to mitigate the adverse effects of leaks. Among these additives, magnesium oxide (MgO) stands out for its ability to reduce drying shrinkage through structural modifications in the cement matrix. Simultaneously, SBR Latex, another important additive, acts to minimize gas migration due to its polymeric microstructure while also strengthening acid resistance and enhancing microstructural cohesion. This study aims to deepen the understanding of the interaction between MgO and SBR Latex additives in cement slurries, employing an experimental design to substantiate and expand upon the analyses conducted. The results reveal a synergistic integration of these additives, with MgO acting as an effective agent in reducing drying shrinkage and gel formation, thereby contributing to the strengthening of shear strength. Conversely, SBR Latex provides elasticity to the slurry, although with a slight compromise in compressive strength, with a relatively limited effect on shear strength. The strategic combination of these additives results in improvements in the mechanical integrity of cement slurries, a positive advancement in the context of petroleum well cementing operations. Thus, this study not only highlights the individual properties of MgO and SBR Latex but also offers valuable perspectives for the careful formulation of cements, with potential applications in challenging operational environments in the oil industry.

A New Method for Constructing the Protection and Seepage Control Layer for CSGR Dam and Its Application

Effective seepage control is crucial for maintaining the structural integrity of Cemented Sand, Gravel and Rock (CSGR) dams. Traditional methods using conventional concrete (CVC) or grout-enriched roller-compacted concrete (GERCC) are costly and disruptive. This paper presents a novel technique for constructing the protection and seepage control layer in Cemented Sand, Gravel and Rock (CSGR) dams. The method involves grouting and vibrating the loosened Cemented Sand, Gravel and Rock (CSGR) material to create vibrated grout-enriched Cemented Sand, Gravel and Rock, which performs similarly to concrete. A new surface water stop structure has also been developed for the structural joints. Laboratory tests revealed that Cemented Sand, Gravel and Rock (CSGR) with a vibrating–compacted (VC) value of 2–6 s and a compressive strength of 4 MPa meets design requirements for medium and low dams when the slurry addition rate is 8–12%. The T-shaped surface water stop demonstrated a bonding strength of over 1.8 MPa, withstanding a water pressure of 1.6 MPa. This method, integrated with dam body construction, reduces material costs by about 50% and eliminates construction interference. Specialized equipment for this technique has been developed, with a capacity of 12 m2/h. Implemented in the Minjiang Navigation and Hydropower Qianwei Project and Shaping I Hydropower Station, it has shown significant economic, environmental and safety benefits, promoting sustainable dam construction.

A pilot-scale study on the in-situ remediation of acid mine drainage with supplemental of external nutrition: Performance, heavy metal removal and microbial community evolution

Acid mine drainage (AMD), a common environmental problem around the world, is characterized by low pH, high concentrations of heavy metals and sulfate. AMD treatment technology based on stimulating in-situ microorganisms has received widespread attention, but lack of organic matter is a limiting factor that restricts the remediation by heterotrophic microorganisms such as sulfate-reducing bacteria (SRB). In this study, a pilot scale reactor was set up next to an acid reservoir to evaluate the effect of livestock wastes on the in-situ bioremediation of AMD, focusing on performance assessment, heavy metal removal efficacy, and the evolution of the microbial community. Results indicated that the pH of AMD rises rapidly from 3.23 to 4.11, and metals (e.g., Fe, Cu, and Zn) rapidly got removed in Stage I. However, AMD experienced significant stratification in Stage Ⅱ (biogas slurry supplemented). The pH of surface layer (0.5 m below the surface) gradually dropped to 3.67, and the bottom layer (2.3 m below the surface) remained around 4.1, and the metal removal efficiencies further improved. Microbial communities were dominated by Fe-OB and Fe-RB in surface layer, while SRB dominated in bottom layer. The addition of biogas slurry significantly increased the relative abundance of functional microbe in bioremediation. The growth of SRB in the bottom of the reactor made an important contribution to heavy metal removal. Heavy metals were mainly removed through the formation of insoluble hydroxide and sulfide precipitation and co-precipitation. This study innovatively integrates low-cost, locally sourced livestock waste as nutrient supplements into AMD bioremediation processes, and demonstrated the potential for integrating AMD treatment with livestock waste management, addressing both the nutrient needs for AMD processing and the challenge of livestock waste disposal. The findings contribute to the development of cost-effective and eco-friendly strategies for AMD management while advancing the understanding of microbial mechanisms of in-situ bioremediation.

Synergistic removal of total petroleum hydrocarbons and antibiotic resistance genes in Yellow River Delta wetlands contaminated soil composting regulated by biogas slurry addition

The interactive effects between the emerging contaminant antibiotic resistance genes (ARGs) and the traditional pollutant total petroleum hydrocarbons (TPHs) in contaminated soils remain unclear. The synergistic removal of TPHs and ARGs from composted contaminated soil, along with the microbial mechanisms driven by the addition of biogas slurry, have not yet been investigated. This study explored the impact of biogas slurry on the synergistic degradation mechanisms and bacterial community dynamics of ARGs and TPHs in compost derived from contaminated soil. The addition of biogas slurry resulted in a reduction of targeted ARGs and mobile genetic elements (MGEs) by 9.96%–95.70% and 13.32%–97.66%, respectively. Biogas slurry changed the succession of bacterial communities during composting, thereby reducing the transmission risk of ARGs. Pseudomonas, Cellvibrio, and Devosia were identified as core microorganisms in the synergistic degradation of ARGs and TPHs. According to the partial least squares path model, temperature and NO3− indirectly influenced the removal of ARGs and TPHs by directly regulating the abundance and composition of host microbes and MGEs. In summary, the results of this study contribute to the high-value utilization of biogas slurry and provide methodological support for the low-cost remediation of contaminated soils.

Renovation of grasslands with grass and white clover – Effects on yield and carbon sequestration

There is a pressing need to support farmers' decisions on grassland renovation, based on sound scientific evidence regarding its effects on productivity, herbage quality and soil organic carbon stocks. To quantify these effects a long-term experiment with grass/white clover swards was set up at the Lindhof research farm in Northern Germany in 1995. Treatments included control plots of undisturbed grassland as well as 10 grassland renovations starting after 10 (2005) years and repeated on different plots 10 times until 2019, and without and with addition of slurry (equivalent to 240 kg N ha−1 yr−1). Grassland renovation resulted in a significant drop in biomass production in the first year after renovation, and the slightly higher yields in the third year after renovation could not compensate for this drop. Yields from the year of renovation to three years afterwards were generally lower, with average reductions over the 4-year periods of 2600 kg DM ha−1 for the treatments without slurry and 1500 kg DM ha−1 for the slurry treatments. Differences in herbage quality between permanent and renovated grassland were negligible and generally not statistically significant. The soil organic carbon showed a rapid and significant drop in the year of renovation, followed by a gradual increase. Without slurry application, the initial levels of soil organic carbon stocks could not be reached even after a period of 18 years following renovation, and with slurry application, it took about 8–10 years. Deep ploughing to a depth of 30 cm did not increase the SOC stocks compared with the undisturbed permanent grasslands, suggesting that the topsoil has not reached the carbon saturation level. We conclude that maintaining productivity of permanent grassland without renovation measures is a promising way towards yield stability and natural climate solutions.

Experimental Strategies for Studying Tribo-Electrochemical Aspects of Chemical–Mechanical Planarization

Chemical–mechanical planarization (CMP) is used to smoothen the topographies of a rough surface by combining several functions of tribology (friction, lubrication), chemistry, and electrochemistry (corrosion, wear, tribo-corrosion). The surface layer of interest is structurally weakened by the chemical and/or electrochemical reactions of selected additives in a polishing slurry, and the modified surface is flattened by the abrasion of a polishing pad with or without abrasive particles. The chemically active CMP slurry also serves as a lubricant for polishing and enables planarization at a microscopic level while avoiding the formation of defects at the processed surface. Applications of CMP are wide-ranging in various material-processing technologies and, specifically, it is a critical manufacturing step of integrated circuits. The CMP of metals is a significant part of this processing scheme and is associated with highly complex tribo-electrochemical mechanisms that are now additionally challenging due to various new requirements of the advanced technology nodes. The present review examines the current statuses of experimental strategies for collecting important mechanistic details of metal CMP that are necessary to design and assess CMP consumables. Both traditional and underexplored experimental techniques are discussed with illustrative results, including many previously unpublished findings for certain CMP systems of current interest.

Effect of zero-valent iron (ZVI) and biogas slurry reflux on methane production by anaerobic digestion of waste activated sludge.

This study aimed to improve anaerobic digestion (AD) efficiency through the addition of zero-valent iron (ZVI) and biogas slurry. This paper demonstrated that methane production was most effectively promoted at a biogas slurry reflux ratio of 60%. The introduction of ZVI into anaerobic systems does not enhance its bioavailability. However, both biogas slurry reflux and the combination of ZVI with biogas slurry reflux increase the relative abundance of microorganisms involved in the direct interspecific electron transfer (DIET) process. Among them, the dominant microorganisms Methanosaeta, Methanobacterium, Methanobrevibacter, and Methanolinea accounted for over 60% of the total methanogenic archaea. The Tax4Fun function prediction results indicate that biogas slurry reflux and the combination of ZVI with biogas slurry reflux can increase the content of key enzymes in the acetotrophic and hydrotrophic methanogenesis pathways, thereby strengthening these pathways. The corrosion of ZVI promotes hydrogen production, and the biogas slurry reflux provided additional alkaline and anaerobic microorganisms for the anaerobic system. Their synergistic effect promoted the growth of hydrotrophic methanogens and improved the activities of various enzymes in the hydrolysis and acidification phases, enhanced the system's buffer capacity, and prevented secondary environmental pollution. PRACTITIONER POINTS: Optimal methane production was achieved at a biogas slurry reflux ratio of 60%. Biogas slurry reflux in anaerobic digestion substantially reduced discharge. ZVI addition in combination with biogas slurry reflux facilitates the DIET process.

Development of a Lab-Scale Tribo-Electrochemical Approach for Chemical Mechanical Planarization

During chemical mechanical planarization (CMP), the electrochemical interactions between slurry additives and the polishing substrate metal films favor the formation of easily removable species that are then detached by mechanical abrasion effects of the CMP pad and nanoparticle abrasives in slurry. Yet, neither the mechanical nor chemical aspects alone dictate the CMP process; rather, it is the intertwined dependencies of tribology and electrochemistry that often control the polish performance. This highlights the importance of the functional synergies, otherwise known as tribo-electrochemistry, which has been largely under-explored in the CMP research community.This work discusses the development of a novel small-scale tribo-electrochemical approach for metal CMP. It covers the tool design aspects, tribo-electrochemical measurements such as open circuit potentiometry (OCP) and polarization resistance, and relevance to CMP applications. The system is developed based on a small-scale CMP polisher coupled to a 3-electrode cell design circuit that is connected to a potentiostat. The design utilizes a common type of CMP metal film as the working electrode, with the accompanying pad and slurry consumables serving as baseline for method development. All other process conditions, including rotating speed, downforce, polish-hold duration, and pad conditioning process follow typical CMP standards.The results show tribo-electrochemical responses to the presence of catalyst (C), oxidizer (O), inhibitor (I), and abrasive (A) in the experimental slurries. The data is of significant value in terms of the anodic & cathodic site functions on the CMP metal surface and in the context of material removal. In addition, notable sensitivity to pad texture, downforce, and temperature effects were observed, and removal rate measurements correlated with polarization resistance for varied levels of the O and I additives. In summary, the tribo-electrochemical aspects of CMP have been probed and an innovative analytical approach has been developed and demonstrated.

On-line monitoring of C seed magma using the ITECA Crystobserver to improve performance

A microscope system, the Crystobserver (supplied by ITECA, France), was installed on the C seed evaporating crystallizer at Condong Mill, Australia, to monitor the crystal development in real-time. The system provides a high-quality image and measures important parameters such as average crystal size and number of crystals in the image. Analysis of data collected over two seasons confirms that the system is reliable in obtaining images with sufficient clarity to assist the operators in remotely monitoring the crystal development from shortly after slurry addition. The reliability of the measurements is satisfactory once the crystals are larger than 30 µm through to near the end of the C seed when the crystal density in the screen is high. The operators have found the Crystobserver to be very beneficial, allowing them to take corrective actions such as changing the amount of slurry addition or the purity of the feed syrup more quickly. The software in the system stores historical data from several strikes, including images and key parameters that can be accessed readily. The installation, microscope and software features and potential benefits to a raw sugar mill are described.

(Invited) Advanced Photoelectron Spectroscopy on Battery Materials: Lessons Learnt on Silicon- Containing Electrodes

While Silicon (Si) is being incorporated more and more as an active material in commercial lithium-ion batteries, it is still a topic of intense research and the motivation for these research efforts remains unchanged: Silicon’s large volume expansion during cycling leads rapid capacity fading largely associated with changes in the Si surface chemistry and unstable solid electrolyte interphase (SEI). Using advanced photoelectron spectroscopy (PES) characterization, we have investigated crucial interfaces on Si model systems and Si-containing negative electrodes for Li-ion batteries. Here, we focus on two approaches to influence the SEI composition intrinsically: Binders and electrolytes.Starting with pristine Si powders, we studied the effect of carboxylic acids as electrode slurry additives on the Si surface chemistry before and after electrochemical cycling [1] using synchrotron PES depth profiling. Further, we used photoelectron spectroscopy to confirm cross-linking in poly-acrylic acid-based binder for Si electrodes and showed that the cross-linking agent pentaerythritol had no negative effect on the SEI thus attributing improved cycling performance to increased binder cross-linking [2].In silicon/graphite negative electrodes, we used PES to elucidate the influence of fluoroethylene carbonate (FEC) on the degradation phenomena in electrodes with varying silicon content [3]. Finally, photoelectron spectroscopy provided insights into what happens to the SEI on Si-containing electrodes if we replace the classical electrolyte solvent ethylene carbonate with either FEC or glyoxylic acetal-based alternatives [4, 5].[1] F. Jeschull, H.Q. Pham, A. Ghamlouche, P.K. Thakur, S. Trabesinger, J. Maibach, J. Phys. Energy 2023, 5 (2), 025002. https://doi.org/10.1088/2515-7655/acbbee.[2] J. He, C. Das, F. Yang, J. Maibach, Electrochimica Acta 2022, 411, 140038. https://doi.org/10.1016/j.electacta.2022.140038.[3] A. Ghamlouche, M. Müller, F. Jeschull, J. Maibach, J. Electrochem. Soc. 2022. https://doi.org/10.1149/1945-7111/ac4cd3.[4] L. Gehrlein, C. Njel, F. Jeschull, J. Maibach, ACS Appl. Energy Mater. 2022, 5 (9), 10710–10720. https://doi.org/10.1021/acsaem.2c01454.[5] L. Gehrlein, C. Leibing, K. Pfeifer, F. Jeschull, A. Balducci, J. Maibach, Electrochimica Acta 2022, 140642–140642. https://doi.org/10.1016/j.electacta.2022.140642.

Soil enzyme activities in heavily manured and waterlogged soil cultivated with ryegrass (Lolium multiflorum)

Extended waterlogging (WL) conditions can alter soil enzyme activities and their role in maintaining healthy soils. We assessed the effects of soil moisture regimes (field capacity [FC] and WL) and phosphorus (P) rates (0, 15, 30, 45 kg available P ha–1) on ( i) soil enzymes and microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and microbial biomass P (MBP); and ( ii) dissolved organic carbon (DOC) and total dissolved nitrogen (TDN). The treatments were tested in a 4-month greenhouse experiment using intact soil columns under annual ryegrass ( Lolium multiflorum). WL decreased the activity of β-glucosidase and acid phosphomonoesterase but increased N-acetyl-β-glucosaminidase in soils. These changes were associated with changes in MBC, DOC, MBN, and TDN, but not MBP. Anoxic conditions in WL soil promote the activity of anaerobes and contribute to the reduction of Fe oxyhydroxides and the release of DOC, TDN, and P in the soil solution. The activity of the extracellular enzymes decreased in WL with additions of slurry indicating adequate supply of C, N, and P. Our results also showed that both enzyme activities and microbial biomass were restricted in the upper soil layer with limited downward movement along the soil profile. We can conclude that since these enzymes control the hydrolysis of cellulose, phosphomonoester, and chitin, soil moisture influences the direction and magnitude of C, N, and P in manured and waterlogged soil cultivated with ryegrass.

Can crop yields be secured while reducing phosphorus accumulation in soil? Assessing decades of contrasting fertilizer strategies.

ContextA balanced phosphorus (P) use in agriculture, where P fertilizer input matches crop offtake, is necessary to avoid accumulation of P in soil that is a chronic source for diffuse P loss. Moreover, mineral P fertilizers produced from rock phosphate is a limited resource, and identification of alternative P fertilizer sources such as animal manures that secure yields without P surpluses is therefore essential for sustainable P use. ObjectiveThe objective was to explore crop productivity and soil P accumulation after long-term input of different P fertilizer sources. Moreover, Olsen-P contents in soil were determined to evaluate if crop yields and P balances were reflected in measures of available P. MethodsOn a coarse sandy soil installed in lysimeters under field conditions, crop yields and P surpluses from 1992 to 2022 were quantified as affected by P fertilizer source (annual additions of solid pig manure, pig slurry and mineral fertilizer) since 1975. All lysimeters received mineral nitrogen (N) fertilizers according to the crop demand. Olsen-P contents in the upper soil layer (0–25 cm) were measured over three decades, and vertical distribution of P in soil down to 140 cm depth was studied at the end of the experimental period. ResultsFor oats, barley, pea and beet root, long-term fertilization with solid pig manure at a rate of 15 kg P ha-1 year-1 resulted in similar yields as after fertilization with 30 kg mineral P ha-1 year-1. After 30 years, the build-up of P in soil was much lower after solid pig manure inputs (accumulation of 8 kg P ha-1) than after mineral P fertilization (accumulation of 51 and 434 kg P ha-1 in soil receiving 15 and 30 kg mineral P ha-1 year-1, respectively). The long-term fertilizer treatments affected Olsen-P levels in the upper soil layer with highest Olsen-P contents (>40 mg P kg-1) after fertilization with 30 kg mineral P ha-1 year-1. Only maize benefitted from high Olsen-P levels and generous input of mineral P, whereas the yield potential for the other crop types could be reached at low to moderate Olsen-P levels after long-term additions of solid pig manure. More P was found in the deep soil layers (65–140 cm) after addition of pig slurry than solid pig manure. ConclusionsThe results showed that solid pig manure was a valuable P source that had the potential to replace mineral P fertilizers without compromising crop productivity, while ensuring low P surpluses. ImplicationsThis study suggests that the Olsen-P test could not stand alone in predicting P requirement but should preferably be supplemented with knowledge on fertilizer source, crop type and P offtakes to ensure a more balanced fertilizer P use.

Comparative Study of Plug and Abandonment Using Balanced Plug Cementing Method: Case Study of Well “NV-01” Field “NS”

The NOV-01 well is a directional well that has technical problems (fish), namely the stuck pipe problem and the problem of high land use operational costs. Based on the results of the evaluation of the economic and risk technical aspects, a plug abandonment (PA) was carried out for the NOV-01 well. The purpose of this research is to compare the 3 stages and 5 stages in PA work and their influence on work program planning and budgeting. The research methodology is qualitative and quantitative. The NOV-01 well plug abandonment activity is carried out by preparing a work program plan such as determining the depth interval of the well to be plugged, the volume of cement slurry additives, as well as the rig method which all refer to the existing standards and regulations, namely SNI 13-6910-2002 and NORSOK D-010. The results of a comparative study on PA planning at 3 stages required 279 sacks of cement and 450 sacks of cement at 5 stages with a density of 15.8 ppg. PA on well NOV-01 uses the rig method with a capacity of 450 HP. For 3 stages it takes 9 days and 5 stages for 11 days. Comparison of estimated costs for PA of NOV-01 well, namely 3 stages of IDR 6,062,977,890.31- and 5 stages of IDR 8,374,824,218.62-. Well NOV-01, PA which is suitable is 5 stages because there is an overpressured zone so that the cement plug is isolated.

Two-Direction Prediction Method of Drilling Fluid Based on OS-ELM for Water Well Drilling

In this study, a drilling fluid prediction method based on an online sequential extreme learning machine (OS-ELM) is proposed, which is prepared for water well drilling on the muddy clay formation of Tarim Basin, Qinghai Province. First, we investigated the mechanism linking mix ratio to fluid performance, allowing us to employ an OS-ELM algorithm derived from the extreme learning machine. Particularly, the proposed prediction method is bidirectional to identify an appropriate slurry formulation. The forward prediction model is established to predict the fluid performance, where the mud additive contents are inputs, and the drilling fluid properties parameters are outputs. Correspondingly, the backward prediction model is established to modify the slurry formula, where differences in the drilling fluid properties are inputs and percentages of slurry additives amount are output. The simulation results show that the two-direction OS-ELM prediction model can better predict the drilling fluid properties in water well drilling.

Effects of Biogas Slurry Application on Soil Microbial Communities Structure and Function During Wheat-rice Stubble Period

To reveal the effects of biogas slurry application on soil microbial community structure and function, a soil column experiment was constructed with three treatments[(no N addition, CM; conventional fertilization, SN; biogas slurry addition, SZ)]. The differences in composition, diversity, and structure of bacterial and fungal communities on day 1 and day 21 after soil flooding were evaluated, and their functions were predicted using Illumina high-throughput sequencing technology. The results of the analysis of α diversity showed that the fungal α-diversity indexes of CM, SN, and SZ treatments on day 1 were significantly higher than those on day 21, and there was no significant difference among the three treatments. However, the bacterial Simpson index differed among the three treatments on day 21, with SZ-21 showing a higher Simpson index but lower Chao1 index compared with those of SZ-21. The analysis of bacterial community structure showed that Firmicutes, Chloroflexi, and Actinobacteria in the SN-1 treatment were different from those in the other treatments on day 1, whereas the relative abundance of bacterial phyla in the SZ and SN treatments were similar on day 21. The analysis of fungal community structure showed that the relative abundance of Ascomycota and Zygomycota in the SZ-1 treatment were higher than those in the SN-1 and CM-1 treatments on day 1. The relative abundance of Ascomycota in the SN-21 and SZ-21 treatments were lower, whereas that of Zygomycota were higher compared with that in CM-21. The analysis of NMDS showed that the composition of bacterial and fungal communities in the SN and SZ treatments showed a gradually similar trend. The PICRUSt analysis showed that the function of the soil bacterial community was similar in the CM, SN, and SZ treatments. The FUNGuild function prediction reflected that the main differences in trophic type between the SN-21 and SZ-21 treatments occurred in saprotroph and pathotroph forms. Therefore, biogas slurry addition in the wheat-rice stubble stage could contribute to balancing soil nutrients and maintaining soil ecological function to a certain extent, but there may still be a risk of fungal disease.

Effect of conditioning schemes on mechanical properties of EPB shield soil

Shearing conditioned sands under different pressure conditions requires understanding their mechanical properties with various conditioning schemes to ensure feasible conditioning during earth pressure balance (EPB) shield tunnelling in sandy strata. This paper investigates the effect of bentonite slurry and foam, conditioned with sodium carboxymethyl cellulose (Na-CMC), on the workability of sand with varying water content, to obtain preliminary conditioning schemes. The conditioned sands with suitable workability are tested using a pressurized vane shear apparatus to obtain their mechanical properties, including compressibility, resilience, and shear strength before and after resiling. Results indicate that Na-CMC can reduce filtration loss of bentonite slurry and foam expansion ratio (FER) of foam, whereas enhance the stability of them. The foam injection ratio (FIR) of foam-conditioned sands and the maximum slurry addition of slurry-foam-conditioned sands decrease linearly with increasing the initial water content of sand, provided the conditioned sands have suitable workability. Increasing the FIR can remarkably increase the void ratio of conditioned sands, which maintains high compressibility and resilience, and low shear strength before and after resiling. The addition of bentonite improves the workability of sand. The conditioning schemes are feasible when the total stress is lower than a specific critical value. The critical total stress can be increased by increasing FIR and reducing the water content of sand or slurry-conditioned sands. This paper provides critical guidance for the design of conditioning schemes.

Effect of main functional groups of cement slurry additives on the stability of methane hydrate: Experiment and molecular dynamics simulation

There are a lot of hydrates in deep-water and shallow layer, which accumulate at relatively shallow depths (<100–120 m). During cementation in the deep-water shallow formation, the free inorganic ions and organic molecules in the cement slurry filtrate enter the formation via percolation, which may affect the stability of the hydrate. The free organic matter in cement slurry acts mainly as retarder, fluid loss additive and dispersant. First, the representative fluid loss additive BXF-200 L, retarder PC-H21L, and dispersant PC-F41L were selected for infrared spectroscopy. Then, the influence of BXF-200 L, which contains all the previously mentioned functional groups, was studied for its impact on hydrate stability using an experimental method. Second, a molecular dynamics simulation method was used to study the adsorption properties of the functional groups on the surface of sI methane hydrate under canonical (NVT) ensemble, which it is the most widely distributed hydrate type in nature. What is more, in order to characterize the influence of functional groups on the decomposition of methane hydrate, the molecular conformation, mean square displacement (MSD), diffusion coefficient (D) and adsorption energy (Eadsorption) were calculated using the dynamics simulation trajectory of sI methane hydrate.The experimental results showed that the main functional groups in cement slurry filtrate additives were carboxyl, sulfonate, and acylamino groups. Further, BXF-200 L can promote hydrate decomposition. Subsequently, the simulation results showed that under the same conditions, the adsorption energy of sulfonate group on the surface of methane hydrate was the largest and the adsorption capacity was the greatest. When the concentration was ≤ 1 mol%, among the three functional groups, acylamino had the most obvious promoting effect on the decomposition of sI methane hydrate, and the hydrate decomposition rate increased by 16.31%. When the concentration was more than 1 mol%, the decomposition rate of hydrate was increased under the interaction of carboxyl, acylamino, and sulfonate groups, by 12.49%, 19.46% and 27.74%, respectively, compared with that under pure water-hydrate system.

Nanohybrid emulsions stabilized with calcium phosphate oligomers prepared by self‐emulsification technology for ultra‐high abrasion resistance coating

AbstractPolyethylene waxes are low molecular weight polyolefin synthetic waxes with outstanding mechanical properties, lubricating performance, and chemical stability, which are widely used in various industrial fields. The nonpolar nature of polyethylene waxes leads to low surface energy and poor compatibility with polar materials, which limits their development applications. Therefore, developing composites with better mechanical properties is essential to overcome this drawback. In this work, calcium phosphate oligomers (CPO) are employed to stabilize nano‐emulsions of polyethylene wax modified with maleic anhydride. The emulsification of emulsions was investigated under different NaOH dosages, temperatures, emulsification times, and rotational speeds. The prepared emulsions are used as additives in polyurethane coatings and starch slurries. The CPO can reduce the particle size of the nanohybrid emulsions and greatly improve the abrasion resistance of some polymer films as additive agents. The organic and inorganic units were homogeneously combined with properties of a complete and continuous organic–inorganic network. The emulsions exhibit ultra‐high abrasion resistance when applied to polyurethane coatings and starch pastes, broadening their range of applications.

Interphase formation with carboxylic acids as slurry additives for Si electrodes in Li-ion batteries. Part 1: performance and gas evolution

Rendering the solid electrolyte interphase and the inter-particle connections more resilient to volume changes of the active material is a key challenge for silicon electrodes. The slurry preparation in a buffered aqueous solution offers a strategy to increase the cycle life and capacity retention of silicon electrodes considerably. So far, studies have mostly been focused on a citrate buffer at pH = 3, and therefore, in this study a series of carboxylic acids is examined as potential buffers for slurry preparation in order to assess which chemical and physical properties of carboxylic acids are decisive for maximizing the capacity retention for Si as active material. In addition, the cycling stability of buffer-containing electrodes was tested in dependence of the buffer content. The results were complemented by analysis of the gas evolution using online electrochemical mass spectrometry in order to understand the SEI layer formation in presence of carboxylic acids and effect of high proton concentration.