Silicate Pastes Research Articles

Удосконалення механізму притирання вільним абразивом за допомогою використання силікатного складу

The results of an experimental study are presented that explain and confirm the mechanism of lapping friction surfaces with a silicate abrasive composition.
 It is shown that the stability of the silicate lapping paste over time can be achieved by introducing ferric trichloride (FeCl3), which in this case is a thickener of liquid glass and also has high hygroscopic properties. The adhesive properties of the silicate paste are improved by the addition of lubricant 1-13. This grease was chosen due to its water solubility. To increase the abrasive ability of the silicate paste, an abrasive powder was introduced. 
 It was found that the lapping performance of the silicate composition and the quality of surfaces are higher than when treated with the «KT» paste, which is currently used for lapping automobile engine valves. Based on the results of the study, the mechanism of lapping friction surfaces with a silicate paste is presented. The mutual movement of the surfaces results in cutting and scratching of the highest peaks of the bumps by the abrasive grains. When silicon oxide (SiO2) is added to the abrasive material, its particles are coated with silicon oxide. This is because liquid glass solutions have a high adhesive force and low surface tension. At the points of contact between the abrasive particles, the temperature rises, and since there is SiO2 around the abrasive, when the latter enters the contact zone, amorphous silica (SiO2) is formed. Since the abrasive grains are coated with a silicon oxide film, SiO2 penetrates into the cavities of micro-irregularities and adheres to the surface under repeated exposure to the abrasive. Thus, the surface to be treated is saturated with silicon oxide, which leads to an increase in its quality after grinding with a silicate composition.
 It has been proven that high surface quality is formed by amorphous silica. To confirm this mechanism, chemical and X-ray spectral analyses of the samples were performed, which showed the presence of SiO2 on the treated surface and a "strong bond" of silicon compounds with the metal surface layer. 
 It was found that the high quality of the surface is also due to the shape of abrasive particles and wear products. It has been confirmed that with the variable movement of surfaces relative to each other, abrasive grains take on a new position each time. At the same time, they are worn from all sides and acquire a rounded shape, and are simultaneously enveloped by a SiO2 foil.

Characteristic microstructural phase evolution and the compressive strength development mechanisms of tricalcium silicate pastes under various initial carbonation curing environments

The effects of various initial carbonation curing environments on the phase evolution and resulting mechanical characteristics of tricalcium silicate paste were studied. For the analyses of the reaction products and microstructure, synchrotron X-ray diffraction, thermogravimetry, Fourier transform-infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy and high-resolution X-ray computed tomography were utilized. C3S cured under carbonation environment pressurized by 0.1 MPa showed excellent mechanical properties owing to the highest degree of reaction and homogeneous generation of CaCO3 with low-Ca/Si calcium silicate hydrates, resulting in a dense matrix with refined pore structure. C3S paste treated under other carbonation conditions underwent deteriorative microstructural phase transitions, including void evolution by decalcification of C–S–H and an inhomogeneous composition of crystalline phases, resulting in inferior properties.

Experimental study of the possibility of using silicate paste to increase the durability of automobile engine parts

Experimental study of the possibility of using silicate paste to increase the durability of automobile engine parts

Preparation and mechanism analysis of nanocrystalline cellulose-tricalcium silicate paste composite with high electromagnetic transmission performance

The tricalcium silicate (C3S) paste with high electromagnetic transmission performance is prepared by addition of nanocrystalline cellulose (NCC), and the enhancement mechanism of electromagnetic transmission performance is revealed. The water to cement ratio (W/C) and the contents of NCC are 0.5 and 1 wt%-4wt%, respectively. The results show that the electromagnetic transmissivity of the C3S paste improves with an increase in NCC content. At the frequency of 3.94 GHz, when the NCC contents are 3 wt% and 4 wt%, the electromagnetic transmission coefficient increases by 113.85% and 153.6%, respectively. The enhancement mechanisms of electromagnetic transmission performance of NCC-C3S pastes are as follows: (1) the polymerization degree of C–S–H and the Van der Waals force between the globules increase; (2) the total volume proportions of low electromagnetic loss C3S and Ca(OH)2 increase; (3) the conductivity of C3S pore solution and the volume proportions of water decrease; (4) the pore volume proportion of the non-harmful pores for electromagnetic energy loss increases.

Success Rate of Direct Pulp Capping with Conventional Procedures Using Ca (OH)2 and Bioactive Tricalcium Silicate Paste vs. Laser-Assisted Procedures (Diode 980 nm, CO2, and Er: YAG)

Direct pulp capping (DPC) is reliable in pulp exposure management. Objective: This study aimed to assess the success rate of DPC materials and different laser protocols. The included procedures were CO2 laser (n = 1147), Er: YAG laser (n = 69), and 980 nm diode laser (n = 124), on the one hand, and Ca (OH)2 (n = 376) and bioactive tricalcium silicate paste, on the other (n = 279). Materials and methods: Data from 1995 DPC cases were included. For laser groups, irradiation was used to coagulate the pulp exposure followed by Ca (OH)2 placement. Data with follow-up at 12, 24, and 36 months post-treatment were included. The irradiation parameters for the CO2 laser were as follows: energy density per pulse of 141 J/cm², 1 W power, 0.3 mm beam diameter, 100 ms pulse duration, and 1 Hz, and a series of five pulses maximum were delivered during 5 s. For the 980 diode lasers: 1.5 W power, continuous wave (CW), 400 μm fiber diameter, contact mode, 190.98 W/cm2 power density, and total delivered energy density of 2387 J/cm2. For the Er: YAG laser: 0.5 W output power, 9.95 J/cm2 energy density, a beam diameter of 0.8 mm, 300 µsec pulse duration, 10 Hz, non-contact mode, irradiation with air without water spray, and an average irradiation time of 8–10 s. Results: At the 3-year follow-up, the success percentages were as follows: CO2 (88.01%) > Ca (OH)2 (75.72%) > diode (70.01%) > Er: YAG (54.55%) > bioactive tricalcium silicate paste (51.1%). The timing of permanent filling (immediate or delayed), patient age, size of pulp exposure, tooth type, and exposure etiology significantly affected the success rate. Patients aged ≤ 35 years presented higher success (70.91%) compared to those ≥ 36 years (61.2%). Immediate permanent fillings increase the success rate (71.41%) compared to delayed permanent fillings (65.93%). Exposure in molars and premolars significantly lowers the success rate (60.3%) compared to canines and incisors (72.1%). Idiopathic pulp exposure presented higher success (72.58%) compared to caries-related causes (63.7%). Conclusion: The highest success rate was in the CO2 laser group followed by the diode and Ca (OH)2, Er: YAG, and bioactive tricalcium silicate material (biodentine) groups. The age factor, filling timing, size of exposure, tooth type, and exposure etiology can significantly affect the success rate of DPC.

A systematic review on the effect of silver diamine fluoride for management of dental caries in permanent teeth.

The objective of this review is to assess the available literature systematically related to the effect of silver diamine fluoride (SDF) for the management of occlusal and root carious lesions in permanent teeth regardless of age. MATERIALSANDMETHODS: This systematic review was conducted according to the Cochrane Handbook for Systematic Reviews of Interventions and Preferred Reporting Items for Systematic Review and Meta-Analyses statement. A literature search was performed usingPubMed/MEDLINE, Cochrane Central Register of Controlled Trials, Web of Science, DOAJ, and Open Gray with no language restrictions up to December 2022. Three reviewers critically assessed the studies for eligibility. Any disputes between the reviewers were handled by a fourth independent reviewer. The quality assessment and data extraction of the studies were performed. A total of 2176 studies were screened. The titles and abstracts of the studies were then reviewed (n = 346), and 52 studies met the search criteria. Following the full-text review, 11 studies investigated the effect of SDF against other treatments such as chlorhexidine, sodium fluoride, ammonium bifluoride, tricalcium silicate paste, casein phosphopeptide amorphous calcium phosphate, glass ionomer cement (GIC) combined with fluoride varnish, resin-modified GIC, and atraumatic restorative treatment were assessed. Within the limitations of this review, the use of SDF is promising with high preventative fractions in permanent teeth of children and older populations when compared to other topical applications such as dental varnish containing sodium fluoride.

Quantitative study on the dielectric properties of tricalcium silicate pastes under different W/C

C3S (tricalcium silicate) pastes with water-cement ratio (W/C) of 0.23, 0.3, 0.4 and 0.5 were designed, and the influence of the dielectric properties of C3S paste were quantitatively analyzed. The results show that when the W/C is 0.23, the real part of permitivity of the C3S paste is the smallest. With increases of the W/C, the real part of permitivity of the C3S paste decrease, and the loss tangent increases. The real part of permitivity of C3S paste decreases with the increase of Ca(OH)2 and pore phases, and increases with the increase of C3S and CSH gel phase. The permitivity of C3S paste decreases most due to increase pore phase (about 4 times that of Ca(OH)2 phase), and increases most due to increase CSH gel phase (about 6.6 times that of C3S phase). The dielectric weight coefficient proposed in this study can well predict the changing trend of the real part of permitivity of C3S pastes with different W/C. Finally, based on the Thermogravimetric analysis (TGA), Scanning electron microscope (SEM), Mercury intrusion porosimetry (MIP), N2 adsorption and 29Si magic angle spinning nuclear magnetic resonance (29Si NMR) test results, the reasons of electromagnetic loss changes of C3S pastes with different W/C were analyzed from the molecular structure of CSH gel, the crystalline products and the pore structure of C3S paste.

Hydration kinetics and microstructure evolution of NaCl-mixed tricalcium silicate pastes

The hydration kinetics of tricalcium silicate (C3S) pastes mixed with different concentrations of NaCl solutions were investigated by performing isothermal calorimetry tests. At the same time, the Boundary Nucleation and Growth (BNG) model was used to analyze the calorimetry data. The model fitted well with the calorimetric results. C3S pastes mixed with NaCl solutions followed a similar reaction path to those prepared with DI water, with an accelerated reaction rate as the NaCl concentration increased. The specific parameters, such as the induction and acceleration durations, were quantified, and the relationship was established. The BNG modelling results indicated that the increasing NaCl concentration significantly increased the nucleation rate of the hydration products while decreasing their growth rate slightly. That was supported by the SEM and STEM observations. The presence of NaCl modified the morphology of the early-age calcium silicate hydrates (C-S-H) to relatively shorter and thinner fibres, which had a more compact microstructure and higher micromechanical properties than those in pure C3S pastes.

Long-term evaluation of early-enamel lesions treated with novel experimental tricalcium silicate paste: A 2-year randomized clinical trial.

The aim of the current study is to evaluate the remineralization potential of experimental tricalcium silicate (TCS) paste in comparison with more popular remineralizing agents like silver diamine fluoride potassium iodide (SDF-KI) and casein phosphopeptide amorphous calcium phosphate (CPP-ACP) on early enamel lesions. Forty-five patients in the age range of 15-50 years had early enamel lesions on the buccal surface of molar teeth. The patients were randomly divided into three treatment groups (SDF-KI, CPP-ACP, and TCS group) with 15 patients per group. Lesions were evaluated clinically by DIAGNOdent pen immediately and after 3,6,12, and 24 months of treatment. The study was completed with 45 patients and 92 teeth. Twice-daily application of CPP-ACP and TCS paste showed a significant remineralization effect on early enamel lesions after 24 months (p< 0.001). Also, annual application of SDF-KI showed a significant remineralization effect after 24 months (p< 0.001). There was a significant difference between (SDF-KI and CPP-ACP) and (SDF-KI and TCS) at the different follow-up periods 3,6,12, and 24 months (p< 0.001). Meanwhile, there was no significant difference between CPP-ACP and TCS at the mentioned follow-up periods (p> 0.05). TCS showed potential remineralization for early enamel lesions. Experimental TCS is a promising remineralizing agent for management of early enamel lesions.

Експериментальне дослідження впливу зернистості абразиву силікатної пасти на якість поверхонь тертя

Currently, many technological methods have been developed to change the structure and properties of surface layers of metal in the desired direction or to create layers with predefined properties. The use of these methods can increase wear resistance, resistance to fatigue and other performance properties of automotive parts. One such method is grinding with abrasive compounds. Grinding technology consists in applying abrasive compositions on the surface of the part and subsequent machining using special devices.The results of experimental research of influence of granularity of abrasive of silicate paste on quality of friction surfaces are resulted in work. Silicate compositions with electrocorundum abrasive of different grain size were made for the study. In order to compare the performance of silicate paste, the existing abrasive pastes «KT» with abrasive titanium carbide abrasive of similar grain size were selected. The research was performed on a special installation, which allows to reproduce with high accuracy the process of processing the abrasive composition in the laboratory. The evaluation was based on the duration of grinding, metal removal and surface quality. Stabilization of the coefficient of friction showed the completion of the grinding process.The study confirms that with increasing grain size of the abrasive silicate composition increases the time of formation of the surface layer and the amount of metal that is removed. It is proved that the high quality of the surface after treatment with silicate composition is due to the appearance in the grinding process of amorphous silica (SiO2), which enhances the work of abrasive grains and reduces the action of the scratching abrasive. Under the action of abrasive particles, SiO2 enters the depressions of the treated surface and adheres to the surface. It is established that the productivity of grinding with silicate composition is 1.5 times higher than when treating surfaces with «KT» paste. It was found that when treating surfaces with a silicate composition with electrocorundum abrasive, the removal of metal is 1.8 times less than when treating with «KT» paste. It is proposed to assign an allowance for treatment with silicate paste from 0.035 to 0.07 mm.

Remineralization of early enamel lesions with a novel prepared tricalcium silicate paste

To evaluate the remineralization potential of prepared tricalcium silicate (TCS) paste compared to silver diamine fluoride-potassium iodide (SDF-KI) and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on artificial enamel lesions. Thirty permanent sound molars were collected for the study. After cleaning, root cutting, and applying acid-resistant nail varnish, leaving a 4 × 4 mm buccal window, the teeth were subjected to demineralization process. The teeth were divided into three treatment groups (n = 10). In each group, the teeth were sectioned buccolingually to obtain two halves (30 self-control and 30 experimental halves). The self-control halves were subjected to cross-sectional microhardness (CSMH), energy-dispersive X-ray spectroscopy at 50, 100, and 150 µm from the external enamel surface, and micromorphological analysis at the superficial enamel surface. The experimental halves were subjected to the same tests after 30 days of remineralization. Three-way analysis of variance (ANOVA) outcomes showed no significant difference in CSMH after treatment among the three different groups at the different levels (p > 0.05). Meanwhile, three-way ANOVA outcomes showed a significant difference in calcium/ phosphate ratio after treatment among the three different groups at the different levels. (p < 0.05). The tricalcium silicate paste used in this study showed potential remineralization in subsurface enamel lesions.

New insights into the effect of gypsum on hydration and elasticity development of C3S paste during setting

Gypsum has been known to regulate cement setting since more than 100 years, whereas the understanding of the physio-chemical mechanism remains incomplete. Here, we investigated the influence of gypsum on elasticity evolution of fresh tricalcium silicate (C3S) paste through small amplitude oscillation shear method. Isothermal calorimetry, X-ray diffraction, 1H nuclear magnetic resonance, and zeta potential measurements were performed to explore the corresponding changes in hydration, microstructure, and colloidal interaction. It was found that incorporating gypsum is beneficial for inter-particle agglomeration by significantly weakening electrostatic repulsion force between particles, which accelerates elasticity development in the early period of setting. Although the retardation effect of gypsum on C3S hydration hinders the further development of elasticity in the later period, the more divergent needle-like calcium silicate hydrate (C-S-H) and the stronger cohesion of the C3S particle network in presence of gypsum lead to a higher elasticity at the same hydration degree.

Rheology and microstructure development of hydrating tricalcium silicate - implications for additive manufacturing in construction

Dielectric RheoSANS measurements are conducted on hydrating triclinic and monoclinic tricalcium silicate pastes with and without a sucrose admixture to simultaneously probe the changing microstructure by small angle neutron scattering (SANS), rheology, and electrical conductivity. The average total surface area of nanoscale calcium silicate hydrate (C-S-H), determined from fractal models fitted to SANS data, at the setting time is estimated to be (17.1(56)) m2 cm−3, independent of C-S-H polymorph or retardation of the hydration reactions. The growth rate of C-S-H with respect to the degree of hydration of the triclinic tricalcium phase is approximately 48 % less than the monoclinic tricalcium silicate phase, a result that may be attributed to the increased number of fine grains in the monoclinic C3S paste. Developing an understanding between the microstructural changes of cement paste and engineering material properties is a critical first step toward engineering cement phase compositions.

Exfoliation of hexagonal boron nitride nanosheets in low-modulus concentrated alkali silicate pastes

We herein demonstrated the exfoliation of hexagonal boron nitride (h-BN) into nanosheets (BNNSs) by using concentrated low-modulus water glass (WG, SiO2/Na2O ratio = 1.6) as high viscosity exfoliating medium. The process led to BNNSs yield of nearly 30%. As the sheared suspension was neutralized with HCl, BNNSs with lateral size of approximately 250 nm and narrow size distribution, were found to align into perfectly parallel rows. High-resolution transmission electron microscopy (HR-TEM) analysis confirmed how WG preserved the integrity of the exfoliated BNNS in comparison with an analogous route with sole hydroxide, resulting in a high amount of BNNSs with undamaged structure.

Investigation of spatial nano-structure development of the hardened C3S pastes by serial block-face SEM

Hardened tricalcium silicate (C3S) pastes cured for different times from 12 h to 28 days were studied by serial block-face scanning electron microscopy (SBFSEM) with the region of interest (ROI) of (2.0 × 104) μm3 and their three-dimensional (3D) spatial structures with a voxel size down to 16.6 nm × 16.6 nm × 20 nm were quantitatively analyzed. From these 3D images, the morphological characteristics of different components of the hardened C3S pastes in three-dimensions are observed directly, such as the connected pores and closed pores. Additionally, the degree of hydration and porosity of the samples are measured as well. Results show that the evolution of the degree of hydration reveals the high reactivity of C3S with water. The formation of the pore network is a complex process which includes not only the partition of the open pores but also the continued hydration of C3S in the closed pores, especially the newly formed closed pores during hydration. The quantitative analysis from SBFSEM measurements were compared with those from traditional TG-DSC and MIP, and it proves that SBFSEM has good applicability in the field of cement-based materials.

Effect of grinding on the quantification of bound water in tricalcium silicate

The effect of grinding hydrated tricalcium silicate (C3S) pastes on the bound water content (BWC) measured by thermogravimetric analysis was investigated. The samples were subjected to different curing regimes at 20°C and 40°C at a constant water to cement ratio of 0·5. Hydration reactions were stopped using a freeze drier. To study the effect of grinding, samples were either roughly crushed or finely ground. Although the amount of water measured from the dehydroxylation of portlandite was not affected by grinding, the total BWC increased with grinding. This increase in the measured BWC was not affected by the studied curing regimes and degrees of hydration of C3S. Fine grinding before hydration stoppage using a freeze dryer produced a BWC similar to that of crushed samples. It is proposed that the increase in measured BWC after grinding is due to the confinement of physically bound water in the interlayers of calcium silicate hydrate.

Hydration and microstructure of tricalcium silicate incorporating nano-TiO2

In order to clarify the enhancing mechanism of nano-TiO2 (NT) on tricalcium silicate (C3S) paste, the hydration and microstructure of C3S with and without NT were investigated. Hydration properties were analyzed by setting time, compressive strength, hydration heat, Ca(OH)2 content and relative content of C-S-H. Moreover, the microstructure of C3S paste was studied by pore structure and micromorphology. The results showed that seeding effect of NT promoted the chemical activity as well as hydration of C3S and more NT led to higher hydration degree. Besides, NT can increase the content of Ca(OH)2 and the relative content of C-S-H, which also proved the enhancement effect of NT on C3S chemical activity and hydration. Furthermore, the seeding effect and filling effect of NT decreased total porosity, enhanced density and meliorated the microstructure of hardened C3S paste. Ultimately, the improved hydration and optimized microstructure introduced by NT enhanced the compressive strength of C3S paste.

Determination of atomistic deformation of tricalcium silicate paste with high‐volume fly ash

AbstractWe examined the effect of incorporating high‐volume fly ash on the atomic arrangement and interatomic deformation behavior of calcium silicate hydrates in tricalcium silicate paste upon exposure to external forces. The interatomic structural changes and strains under compressive load were assessed using synchrotron in situ high‐energy X‐ray scattering‐based atomic pair distribution function analysis. Three different types of strains, which were (a) macroscopic strains from gauges on the surfaces of specimen, (b) strains in a reciprocal space (Bragg peak shift), and (c) strains in real space (PDF peak shift), were compared to each other. All monitored and calculated strains for tricalcium silicate‐fly ash (50 wt% fly ash) paste were compared with the counterparts of the pure tricalcium silicate paste. Pair distribution function analysis in the range of r &lt; 10 Å indicated that the atomic arrangement of tricalcium silicate‐fly ash was similar to that of synthetic calcium silicate hydrates followed by that of pure tricalcium silicate paste. Moreover, the pair distribution function refinement results revealed that the calcium silicate hydrate structure in tricalcium silicate‐fly ash paste was similar to tobermorite 11 Å, unlike that in pure tricalcium silicate paste. The interatomic strain of tricalcium silicate‐fly ash in the real space (r &lt; 20 Å) was smaller than that of tricalcium silicate under compression, which suggested that the incompressibility of calcium silicate hydrates at atomistic scale was enhanced by the incorporation of fly ash into it. This was likely to be caused by the increased silicate polymerization of calcium silicate hydrates, which was attributed to the increase in the amount of silicate in their structure via the addition of fly ash.

Analysis of atomistic structural deformation characteristics of calcium silicate hydrate in 53-year-old tricalcium silicate paste using atomic pair distribution function

Although the atomistic structure and the deformation characteristics of calcium silicate hydrates (C-S-H) are of primary interest in cement chemistry, they have not been fully investigated. In this study, pair distribution function (PDF) analysis was conducted on a 53-year-old fully hydrated tricalcium silicate (C3S) paste using in situ synchrotron high-energy X-ray scattering to probe the atomic structural deformation of C-S-H under external loading. The results were compared with those from our previous PDF study of a 131-day-old C3S paste in order to elucidate the effect of aging on the mechanical characteristics of C-S-H. Three different strains measured by the strain gauge, by the lattice shifts (d-spacing) in the reciprocal space, and by the shift of the interatomic distance (r) in the real space were compared. In the range of r < 20 Å, where most of the information was derived from C-S-H, the 53-year-old C3S paste had a higher overall elastic modulus (18.3 GPa) and better resistance to compressive stress than the 131-day-old C3S paste (elastic modulus: 8.3 GPa). Moreover, it was found that the macroscopic strains of the 53-year-old C3S paste were presumably induced by mechanical deformation such as microcracks at the macroscale. The results provide experimental evidence for the atomistic and mesoscale mechanical behavior of C-S-H in the early and late ages.

The Effect of Calcium Leaching on the Chloride Diffusivity of Hydrated Tricalcium Silicate Pastes

Calcium leaching of cement-based materials induces detrimental effects on diffusion properties related to long-term durability. This paper investigates the effect of calcium leaching on the chloride diffusivity of hydrated tricalcium silicate (C3S) pastes. Different concentrations of ammonium nitrate solutions were used to accelerate the calcium leaching of C3S pastes. The degree of alternation of C3S pastes was characterized by Ca/Si. The chloride diffusivity of the leached C3S pastes was obtained by the steady-state electro-migration test. Results show that the chloride diffusivity of the leached C3S pastes increases with the increasing degree of alteration. Compared with the sound C3S pastes, the diffusivity of the leached C3S pastes is increased 1.8-3.6 times depending on the degree of alteration.