Polishing Powder Research Articles

Effect of the Dielectric Characteristics of a Treated Material, a Polishing Powder, and a Disperse System on the Energy of Their Interaction in the Polishing of Optical Surfaces

Effect of the Dielectric Characteristics of a Treated Material, a Polishing Powder, and a Disperse System on the Energy of Their Interaction in the Polishing of Optical Surfaces

Investigating lanthanum flows and stocks in China: A dynamic material flow analysis

Rare earth elements (REEs) are irreplaceable in modern societies due to rising demands, especially amidst the urgent energy transition background. As the first ordered and the second most produced REE, lanthanum is widely used in conventional fields. This study investigates lanthanum flows and stocks in China by conducting a dynamic material flow analysis for the period of 2011–2020. The main results are that: 1) The registered quota production of La from 2011 to 2020 is 235,306 tons, and net La import accounts for 24.79% of the total input flows. 2) The accumulative surplus of La under the circumstance of quota production is 35,929 tons, with the in-use stock being 148,556 tons. 3) China is the net La importer of concentrates (133,769 tons) and net La exporter of primary, intermediate, and final products. The net La export is mainly in the form of primary products (76.27%). 4) The consumption of La increases steadily from 21,708 tons in 2011 to 31,580 tons in 2020. The top 5 applications are FCC (45.58%), rechargeable NiHM battery (16.97%), alloy (10.77%), optical glass (8.95%), and polishing powder (4.86%). Policy suggestions include expanding the demand market, adjusting the quota production system based on REEs, and improving investment in and guidance for R&D.

Conversion coating technology for recovery and reuse of waste Mg alloy polishing powder

The waste dust from Mg alloy grinding not only has the danger of explosion, but also reduces the performance of Mg due to the oxidation and hydrolysis of Mg, which seriously limits the reuse of Mg alloy waste dust. In order to avoid the oxidation of Mg alloy dust and recycle it, four inerting agents, including sodium citrate and sodium alginate, were selected to inertize waste Mg alloy dust. The results show that when used alone, none of the inerting agents can completely prevent the production of Mg(OH)2. After the combination of organic sodium citrate and inorganic sodium silicate, the inerting efficiency of Mg alloy dust can reach 99.4%, which is more than 20% higher than that of any inerting agent used alone. XRD and FTIR results showed that a composite conversion film composed of [SC-Mg] and hydrated magnesium silicate is formed on the surface of waste Mg alloy dust particles, which blocks the contact between external water molecules and Mg2+ ions. Stability test under different conditions showed that the composite conversion film can maintain good stability under different temperatures, disturbance speeds and Cl− concentrations. The inerted Mg alloy dust (0.4 wt% SC+0.2 wt% SS) has been verified in industrial application, and the reuse possibility of residual Mg alloy powder has been confirmed. This study not only provides a simple and effective method for recycling waste Mg alloy dust, but also reduces the explosion risk during dust collection and transportation.

DFT insight into the adsorption behavior of H2PO2 on the reduced Ce0.899M0.111O1.785(111) (M = Ti, Zr) surface

To study the effect of Ti and Zr doping on the reducibility of CeO2(111) substrate and the adsorption of H2PO2 on KDP surface, the O vacancy formation energy of Ti/Zr-doped CeO2(111) surface was calculated using DFT+U method. The adsorption energy, bonding structure and local electronic structure of H2PO2 on Ti/Zr-doped CeO1.963(111) surface was analyzed. The results showed that the O vacancy formation energy of Ti/Zr-doped CeO2(111) surface was reduced and the surface magnetic moment was enhanced. P-O and O-O covalent bonds were formed at the adsorption interface between H2PO2 and the substrates. The adsorption energies of H2PO2 on the reduced substrates were Ce0.899Ti0.111O1.963(111) > CeO1.963(111) > Ce0.899Zr0.111O1.963(111). The adsorption energies of H2PO2 on the substrates containing subsurface O vacancy were greater than those on the substrates containing surface O vacancy. The most stable adsorption site of H2PO2 on the Ce0.899Ti0.111O1.963(111)-sub surface was Oh site, P was bonded with two surface O, and the adsorption energy (7.612 eV) was the maximum, therefore, the Ce0.899Ti0.111O1.963(111)-sub surface was the more suitable for polishing H2PO2 on KDP surface. These results may lead to a better understanding and improving for the Ti/Zr-doped CeO2 polishing powder.

Investigation of performance and modification mechanism of ceramic-polishing-powder-modified asphalt mastic

In this study, ceramic polishing powder (PP) as an industrial waste product, was treated by a silane coupling agent (KH550) and an NaOH solution, and then it was used to prepare the PP-modified asphalts. The performance of the modified asphalts and their modification mechanisms were examined. The results showed that the optimal preparation process was pre-shearing 15 min, and then shearing 60 min at 145°C, 4000 r/min after adding PP. KH550-PP-modified asphalt exhibited the best high- and low-temperature performances, thermal-oxidative aging resistances and anti-water damage performance and the lowest temperature sensitivity. PP was evenly dispersed in the original asphalt, which increased the bee structure and the surface roughness of the asphalt. The surface modifier changed the surface physical properties of the PP particles, which is helpful to achieve co-melting and blending with the original asphalt. However, an effect on the chemical structures of the composite-modified asphalts was not evident.

Coordination-Enhanced Extraction of Rare Earth Metals from Waste Polishing Powder and Facile Preparation of Mesoporous Ce0.8la0.2o1.9

Coordination-Enhanced Extraction of Rare Earth Metals from Waste Polishing Powder and Facile Preparation of Mesoporous Ce0.8la0.2o1.9

Antimicrobial Impact of Different Air-Polishing Powders in a Subgingival Biofilm Model.

Subgingival air-polishing devices (SAPD) can reduce bacterial biofilms and thus support periodontal healing. The authors of this study evaluated the effectiveness of the glycine-based and trehalose-based air-polishing powders in removing pathogenic bacteria in a subgingival biofilm model. We treated 56 subgingival pockets in porcine jaws with SAPD. Subgingival air polishing was performed in three groups of 13 pockets each: I, glycine-based powder; II, trehalose-based powder; and III, water alone. Another group (IV) served as untreated controls. Prior to air polishing, inoculated titanium bars were inserted into the pockets containing periopathogenic bacteria such as Porphyromonas gingivalis and Tannerella forsythia. Remaining bacteria were evaluated using real-time PCR. The numbers of remaining bacteria depended on the treatment procedure, with the lowest number of total bacteria in group I (median: 1.96 × 106 CFU; min: 1.46 × 105; max: 9.30 × 106). Both polishing powders in groups I and II (median: 1.36 × 107 CFU; min: 5.22 × 105; max: 7.50 × 107) showed a statistically significantly lower total bacterial load in comparison to both group IV (median: 2.02 × 108 CFU; min: 5.14 × 107; max: 4.51 × 108; p < 0.05) and group III (median: 4.58 × 107 CFU; min: 2.00 × 106; max: 3.06 × 108; p < 0.05). Both subgingival air-polishing powders investigated can reduce periopathogenic bacteria and thus support antimicrobial therapy approaches in periodontal treatment regimens.

Polishing of precision parts of optical-electronic and laser equipment

The mechanism of interaction of the optical surface with the polishing dispersed system during polishing is investigated. It is established that the energy transfer between them is a consequence of the dipole-dipole interaction in the donor-acceptor system and occurs by the Ferster mechanism. It was found that the decrease in the spectral separation between the treated material and the particles of polishing powder causes an increase in the size of sludge particles and wear particles, which leads to an increase in the roughness parameters Ra, Rq, Rmax of optical surfaces during polishing by polishing dispersed sys-tems. It is shown that the polishing productivity of optical surfaces and the wear intensity of polishing powder particles decrease with increasing corresponding transfer energies, which confirms the main pro-visions of the cluster theory of polishing of nonmetallic materials and the validity of quantum mechanical description of resonant energy transfer mechanism between dispersed material and dispersed system.&#x0D;

Identification Characteristic of Purple Jadeite Treated with Bleaching, Filling and Dyeing

To explore the identification characteristics of purple jadeite that is treated with bleaching, filling and dyeing, the gem microscope, refractometer, UV-Vis-NIR spectropho-tometer, XRF spectrometer, DiamondViewTM, FTIR and Raman spectrometer were used. The results showed that the internal structure of the purple jadeite samples treated with bleaching, filling and dyeing was destroyed, and epoxy resin was detected by infrared spectrometer and Raman spectrometer. Strong Raman peak at 1 596 cm-1 could be the characteristic peak of dyes. Luminescent images showed the characteristic blue-violet fluorescence of the polymers formed by epoxy resin and organic dyes. The UV-Vis spectra of the purple jadeite samples treated with bleaching, filling and dyeing showed the absorption band of 200-350 nm, the absorption peak at 409 nm and the absorption band near 569 nm.The internal structure of the jadeite stained by the purple polishing powder was not damaged, and the purple colour only stained on the surface since the powder particles only remained on the surface. The luminescent images showed pinkish purple fluorescence, which was caused by the purple polishing powder. The strong central absorption band at 558 nm and the weak central absorption band at 611 nm can be seen in the UV-Vis spectra, which are different from the natural purple jadeite.

Experimental Research on Compressive and Shrinkage Properties of ECC Containing Ceramic Wastes Under Different Curing Conditions

Engineered cementitious composites (ECCs) suffer from high shrinkage and low early strength due to large dosage of cementitious materials and slow hydration of fly ash. This study aims to improve compressive properties and reduce drying shrinkage of ECC using ceramic wastes and hydrothermal curing. Experimental results have indicated that ceramic polishing powder (CPP) and recycled ceramic sand (RCS) exert opposite effect on the compressive strength of ECC. Hydrothermal-cured ECC enhances elasticity modulus and compressive strength and reduces later drying shrinkage as compared with that under standard curing. A CPP dosage of 35% and a hydrothermal curing regime with a temperature of 70°C and age of 7 days are recommended for the engineering application of ECC.

Ultrasonic dispersion method used in glass polishing experiment

To solve the problems of low processing efficiency and poor glass surface quality when using rare earth polishing powder to grind super-hard K9 glass. The potential, phase structure, surface morphology, and particle size distribution of the nano-rare earth polishing powder were characterized. Compare the evaluation indexes such as polishing efficiency, surface morphology, and contact angle after the polishing process is changed. The results of the comparative study show that the average surface roughness of the glass after heating ultrasonic polishing process is 0.9064 nm, the polishing rate reaches 0.748 μm/min, the average surface roughness of the glass without heating ultrasonic polishing process is 1.3175 nm, and the polishing rate reaches 0.586 μm/min, the ultrasonic assisted polishing process is superior to the conventional polishing process. The heating ultrasonic method provides experimental basis for precise and rapid processing.

Preparation and characterization of submicron-cerium oxide by hypergravity coprecipitation method

Submicron-cerium oxide particles were synthesized by applying hypergravity using ammonium bicarbonate (precipitant) and cerium nitrate hexahydrate (precursor). The influence of the concentration, pH, dispersant loading, flow rate, rotation speed of the hypergravity rotating bed, calcination temperature, and time on the cerium oxide particle size were examined by zeta potential, solid–liquid contact angle, thermo-gravimetry–differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. The cerium oxide particles were highly dispersed, with an average particle size of 200 nm. Calcining at 650 °C for 1.5 h afforded the smallest particles. The crystallite size and fraction crystallinity increased with prolonged calcination. Crystalline cerium dioxide grew along three crystal planes, forming a complete face-centered cube, affording high hardness and activity of the polishing powder. The optimal conditions were: cerium nitrate concentration: 0.7 mol/L, cerium nitrate/ammonium bicarbonate molar ratio: 1:3, dispersant mass fraction: 3%, cerium nitrate initial pH: 4–5; the precursor solution was adjusted to pH 9 with ammonia water. Hypergravity coprecipitation with 1.5 h calcination afforded submicron-sized cerium oxide with a uniform size distribution using ammonium bicarbonate in an industrially viable process. The simple and low-cost manufacturing process may enable the development of hypergravity-assisted chemical synthesis technology.

Recycling of used alginate impression materials into final polishing powder for methacrylate denture base resins

Recycling of used alginate impression materials into final polishing powder for methacrylate denture base resins

Recovery of lanthanum and cerium from rare earth polishing powder wastes utilizing acid baking-water leaching-precipitation process

A new approach to recover lanthanum and cerium from rare earth polishing powder wastes has been developed in this study. Lanthanum and cerium oxides in the raw materials were converted to sulfate by concentrated sulfuric acid baking at 300 °C, and the roasted product was leached with water at 25 °C for 2 h. Under the optimal conditions, nearly all the rare earth elements in the liquor was precipitated as La(III) and Ce(III) oxalate deca-hydrate with oxalic acid. The oxalate precipitate was then calcined at different temperature (550–950 °C) to prepare the final product- La2O3 and CeO2. X-ray diffraction results provide detailed phase transformation information of rare earth elements during the recovery process. The final product composed of 34.18% La2O3 and 65.66% CeO2 was given the composition and structure analysis. During the whole process, the yield of La and Ce were 99.39% and 89.02%, respectively.

Tooth polishing - A mouthful of history

Tooth polishing continues to be an integral part of clinical practice since the concept of selective polishing was introduced in the 1980s. Polishing essenitiates the removal of stains and plaque bio-film and provides a method for applying various medicaments to the teeth such as desensitizing agents .With passage of time emergence of more efficient and effective devices like jet abrasives have been introduced . Still the role of rubber cups with prophy angles cannot be overlooked as they are still being widely used and provide an economical alternative. A traditional polishing method, i.e. a rubber–cup with prophylaxis paste, has been shown to remove thefluoride–rich outer layer of the enamel thus causing significant loss of cementum and dentin over time. So alternative tooth polishing methods were developed with evidence to support alternative tooth polishing methods, dentists should familiarize themselves with contemporary methods including air polishing. The purpose of this review is to provide a comprehensive overview of recent advancements in air polishing. Clinical Relevance Scientific Rationale of Polishing:Polishing cause the abrasion of tooth surfaces. American dental hygienists association strongly recommends, do polishing of the tooth surfaces, when a dental hygienist or dentist determines a specific need for it. One should understand patient’s expectations they simply like the look and feel of teeth along with the taste and smell are next important factors. Principal findings:Polishing has been evolved from finely ground coral, eggs, shells, ginger or salt. After that various other polishing powders like flour of pumice and calcium carbonate, aluminum oxide (alumina), silicon carbide, aluminum silicate, silicon dioxide, carbide compounds, garnet, feldspar, zirconium silicate, zirconium oxide, and boron. Because of the particle size they were considered to be more abrasive. Practical Implications:With new advances finer abrasive agents with fine pa

Cleaning and Conditioning of Contaminated Core Build-Up Material before Adhesive Bonding.

The objective of this study was to evaluate the effects of different cleaning and conditioning procedures after contamination on the tensile bond strength (TBS) of a luting resin to a core build-up composite resin. Specimens (n = 384) made of a core build-up material were stored for 3 weeks in 37 °C water. Half of the specimens were contaminated with saliva and a disclosing silicone and then cleaned either using phosphoric acid, a pumice suspension, air-abrasion with alumina or polishing powder. Surface conditioning was performed by either using a dentin adhesive, a silane containing primer or a composite resin primer, which resulted in 24 unique combinations of 16 specimens per group. Before measuring TBS, half of the specimens of each group were stored in 37 °C water for 3d or were artificially aged for 150 days. Results show that cleaning with pumice or air-abrasion are superior methods compared to using a polishing powder or phosphoric acid. Silane is an inferior conditioning agent compared to composite or dentin primers. Ideally, after contamination, bonding surfaces should be cleaned with a pumice suspension and conditioned with a dentin adhesive. Those surfaces could also be cleaned and conditioned with air-abrasion with alumina particles and a composite resin primer.

Kinetics study on leaching of rare earth and aluminum from polishing powder waste using hydrochloric acid

In this study, a novel hydrometallurgical process consisting of hydrochloric acid three-stage countercurrent leaching and solvent extraction was proposed to recover rare earth oxide (REO) from the rare earth polishing powder waste (REPPW). The effects of HCl concentration, liquid–solid ratio (L/S ratio), temperature and time on the leaching yields of rare earths (in REO) and aluminum (in Al2O3) were studied. The result shows that the leaching yields of REO and Al2O3 are 90.96% and 43.89% respectively under the optimum leaching parameters of HCl concentration = 8.00 mol/L, L/S ratio = 4 mL/g, leaching temperature = 353 K and leaching time = 180 min. Meanwhile, the leaching kinetics of REO and Al2O3 were investigated in this study. The leaching behaviors of REO and Al2O3 follow a shrinking sphere/core model and the general leaching process is controlled by the surface chemical reaction. The leaching activation energies of REO and Al2O3 are 9.86 and 13.68 kJ/mol, respectively. The leaching yield of each substance in three-stage countercurrent leaching is improved substantially compared with single-stage leaching, with a change from 90.96% to 95.38% for REO and from 43.89% to 46.22% for Al2O3, respectively. Especially, the total concentration of REO in three-stage countercurrent leaching solution is greatly increased to above 300 g/L, and the acidity of which is decreased to ca. pH = 2, which is conducive to subsequent solvent extraction directly. High purity REO (99.92%) is obtained by solvent extraction separation, oxalate precipitation and calcination. The total recovery yield of REO is 85.13%.

Enhancing Cerium Recovery from Leaching Solution of Glass Polishing Powder Waste Using Imidazolium Ionic Liquid

One of the high-tech industries is glass polishing, which is associated with the release of large volumes of wastewater, a rich source of rare-earth metals, especially cerium. In this study, cerium ion recovery from glass polishing powder waste using green solvents for extraction was investigated. Reaction time, temperature, organic to aqueous ratio, extractant concentrations, and the synergistic effects of imidazolium ionic liquids and trioctylphosphine oxide and tributylphosphate as extractants were optimized. The co-extraction of lanthanum, a significant problem in extracting cerium, was reduced by enhancement of their separation factor (~ 17). The cerium-bearing organic solvent was stripped with 0.5 mol/L HNO3 to attain a recovery of cerium by 99.98%. The ionic liquids are useful in the extraction process, enabling higher yields of cerium and reducing the consumption of acids in the stripping stage.

Conversion of diamond polishing powder to high-density isotropic nano-crystalline graphite through spark plasma sintering

Conversion of diamond polishing powders into graphite nano-crystals and simultaneous densification to high-density graphite were achieved through spark plasma sintering at 2000 °C with 45 MPa pressure. The sintered graphite had a density of 1.84 g/cm3 and hardness of 12.1 ± 0.4 HV. The phase evolution was characterized by X-ray diffraction and Raman spectroscopy. Scanning electron microscopy and transmission electron microscopy revealed that the converted high-density graphite consisted of randomly oriented nano-crystalline grains. The formed graphite was also isotropic in nature.

Conversion of cerium and lanthanum from rare earth polishing powder wastes to CeO2 and La0.6Ca0.4CoO3

In the present work, a feasible approach was developed for the recovery of cerium and lanthanum from rare earth polishing powder wastes to synthesize shape-controlled CeO2 and perovskite-type La0.6Ca0.4CoO3 powders. The process proposed here includes six steps: (i) Pre-roasting treatment, (ii) H2SO4 digestion and water leaching, (iii) double salt (NaRE(SO4)2·xH2O) precipitation, (iv) conversion of NaRE(SO4)2·xH2O into RE‑carbonate, (v) oxidation and separation of cerium and lanthanum, and (vi) oxalic salt precipitation conversion and calcinations to synthesize CeO2 and glycine-nitrate combustion process to get La0.6Ca0.4CoO3.The recovery yield for the total process was 91.73% for cerium and 90.45% for lanthanum. In the preparation process of CeO2 and La0.6Ca0.4CoO3, CeO2 powders with controlled shapes were obtained by modifying the final pH value in the precipitate transformation from Ce(OH)4 to cerium oxalate and subsequent calcinations. On the other hand, based on the polarization curves, the prepared La0.6Ca0.4CoO3 exhibited a good catalytic activity for oxygen reduction reaction, showing potential applications in zinc-air batteries.