Research study of the elastic-strength and tribological characteristics of the surface after laser processing of the slurry coatings

The research paper examines the results of applying the proposed method of the laser processing of the composite slurry coating on the steel samples` surface such as 12Kh2N4A-Sh. An increase in the elastic-strength and tribological characteristics` surface occurs as a result of the imposition of several physicochemical processes in the laser-impact zone on the applied composite slurry coating with an epoxy element as the base material with the laser thermal hardening, the diffusion influence on the atomic boron along grain boundaries, carbonization and the formation of a modified surface layer. The conducted research shows the gradient structure of the surface layers. The coating composition varies in the studied samples, however, for all experimental samples, the elastic-strength and tribological characteristics are higher than the corresponding characteristics of the standard steel sample as 12Kh2N4A-Sh, which has undergone the cementation process. The calculated values of the resistance indicators of the elastic and plastic deformation are confirmed by the conducted tribological tests. It is given the higher efficiency of the laser processing method of the slurry coating and it is concluded the prospects of the proposed method.

Research on Optimal Proportion and Performance of Cement-Clay Slurry

For the cement-clay slurry commonly used in dynamic water grouting, consider adding coal ash to optimize the performance of cement-clay slag composite slurry and discuss the reaction mechanism of the slurry through microchemical element analysis; the orthogonal test was used to study the influence of various factors on material setting time, solidification ratio, water segregation rate, and the optimized ratio of the slurry that was obtained by integrating the unconfined compressive strength of grouting concretion body and slurry configuration cost. The results showed that the water-solid ratio had the greatest influence on the comprehensive performance, followed by the amount of coal ash admixture. The best performance of the composite slurry was obtained with a water-solid ratio of 0.8:1 and a cement:coal ash:clay:quicklime:sodium sulfate:water mass ratio of 1:0.45:0.20:0.05:0.07:1.32. Finally, by comparing the mechanical properties of the optimized slurry and the grouting concretion body, it is proved that the optimized slurry has superior performance to meet the general grouting project requirement.

Phenylphosphonate surface functionalisation of MgMn2O4 with 3D open-channel nanostructures for composite slurry-coated cathodes of rechargeable magnesium batteries operated at room temperature

Phenylphosphonate functionalisation is an easy, highly effective strategy to fabricate slurry-coated nanostructured MgMn2O4 cathodes for rechargeable magnesium batteries at active material fractions up to 93 wt% for rechargeable magnesium batteries cycled at 25 °C.

Structural analysis of CaCO3 nanoparticle/pulp fiber composites by tube flow fractionation

Two slurries that consisted of precipitated calcium carbonate (CaCO3) nanoparticles and unbeaten hardwood bleached kraft pulp (HBKP) were prepared via ultrafine bubble and mixing methods. In the ultrafine bubble method, a CO2 gas flow was bubbled into a HBKP slurry that contained Ca(OH)2 to prepare a precipitated CaCO3/HBKP composite slurry. The HBKP/water and precipitated CaCO3/water slurries were prepared separately and mixed to prepare a precipitated CaCO3/HBKP mixture slurry. Each of the two CaCO3/HBKP slurries was separated into five fractions using a tube flow fractionation (TFF) system. The first and second fractions consisted of long HBKP fibers and fiber aggregates. The third fraction had the highest mass ratio of the components in the five fractions, and it had approximately 1-mm-long HBKP fibers. The fourth fraction contained primarily HBKP short fibers and CaCO3 aggregates. Thus, the CaCO3/HBKP components in the slurry were separated adequately by TFF, depending on their hydrodynamic sizes. The average width of each fraction in the CaCO3/HBKP composite slurry was always larger than that of the corresponding fraction from the CaCO3/HBKP mixture slurry, which indicated that precipitated CaCO3 nanoparticles and their aggregates attached stably to long and short pulp fiber surfaces in the composite slurry.

Effect of Ceramic and Nylon Fiber Content on Composite Silica Sol Slurry Properties and Bending Strength of Investment Casting Shell

In order to improve the performance of the investment casting shell, ceramic and nylon fiber was added to the silica sol slurry to study the effect of ceramic and nylon fiber on the liquidity of the silica sol slurry and the bending strength of the investment casting shell. Meanwhile, the fracture surface of shell sample was observed by SEM. The experiment results indicate that the movement viscosity of slurry increases with ceramic and nylon fiber content, increasing from 0 to 0.75 wt.%. The movement viscosity of ceramic fiber composite slurry is higher than nylon fiber composite slurry. The wet and high strength of shell firstly increases then decreases, with an increase of ceramic and nylon fiber content. When the ceramic and nylon fibers’ contents are 0.6 wt.%, the maximum wet strengths are 3.56 MPa and 3.84 Mpa respectively, increasing by approximately 38% and 43%. Moreover, the high strength of shell achieves its highest value, 5.08 Mpa, when the ceramic fiber content is 0.6 wt.%; however, when the nylon fiber content was more than 0.3%, the high strength of the nylon fiber reinforced shell was decreased sharply. Therefore, an addition of ceramic and nylon fiber to silica sol slurry distinctly influences the wet and high strength of investment casting shell.

Developing a Polypropylene Fabric, Silica Fume, and Redispersible Emulsion Powder Cementitious Composite for Dynamic Water Environment

In the dynamic water environment, grouting requires a material with higher strength and anti-washout performance to prevent groundwater inrush. This study aims to develop a dynamic water slurry by mixing polypropylene fiber (PP fiber), silica fume (SF) and the polymer material of redispersible emulsion powder (REP) to the Portland cement. Towards this aim, a series of tests, including strength, gel time, bleeding rate, fluidity, and anti-washout, were conducted to evaluate the effects of SF, PP fiber, and REP on the slurry properties. The test results show that: (1) SF displays significant effects on strength, gel time, fluidity, and bleeding rate of cement slurry. Differently, PP fiber mainly affects the stress–strain behavior of the slurry and can improve the ductility significantly. (2) By mixing SF and fiber simultaneously, the slurry strength can increase by about 30%, and its strain can extend by more than 70%. Meanwhile, the composite slurry possesses great anti-washout properties at a low flow velocity (v ≤ 0.4 m/s), and the grouting retention rate (GRR) can reach up to 98.7%. However, the GRR decreases to a maximum value of 31.3% when v = 0.6 m/s. (3) By mixing the REP into the fiber-SF composite slurry, the GRR can further increase, reaching more than 60% even when v = 0.6 m/s. As a result, the developed fiber-SF cementitious composite slurry, which when mixed with REP, presents a favorable performance in the dynamic water environment.