Polishing Powder Research Articles

The study of process production of polishing powder based on cerium dioxide

Finely divided cerium dioxide powder is an excellent polishing agent for optical glass under intensive processing conditions. Cerium dioxide powder was produced from a mixture of rare earth carbonates by conversion to oxides, reacting with acid to separate a sediment of CeO(OH) 2 from solution containing the trivalent rare earth ions, washing the sediment, and drying and annealing it to produce finely divided CeO 2. Physical and chemical investigations of each stage of the processing were performed. A relation was established between the properties of CeO(OH) 2 (such as degree of fineness and crystal structure) and the properties of the REE oxides that were used. It was shown that very fine REE oxides generate fine CeO(OH) 2. It was also shown that to obtain CeO 2 powder with high specific surface area and perfect crystal structure, the CeO(OH) 2 must be annealed in two steps: (1) dehydration of intermediate CeO 1.5(OH) to produce very fine powder, and (2) dehydration at 800–1050°C.

Study for Recycling of Ceria-Based Glass Polishing Powder

The recycling of ceria-based glass polishing powder by alkali treatment was investigated. Major impurities in the waste, a SiO2 component from fine glass powder and an Al2O3 component from coagulating agents, could be removed easily at 50−60 °C in a 4 mol kg-1 NaOH solution within 1 h. These impurities react with NaOH to precipitate as zeolite at higher temperature. Thus, it is expected that a recycling process which can regenerate polishing powder and convert SiO2 and Al2O3 components into zeolite can be designed.

Production of Rare Earth Polishing Powders in Russia

Production of Rare Earth Polishing Powders in Russia

The Development of a Rare-Earths Bases Polishing Powder Business through Sino-Japanese Cooperation

The Development of a Rare-Earths Bases Polishing Powder Business through Sino-Japanese Cooperation

Microstructure evolution in aluminium-titanium aluminide composite: C.M.Wang, R.Watanabe. (Tohoku University, Sendai, Japan.) J. Jpn Soc. Powder Powder Metall., vol 44, no 12, 1997, 1100–1106. (In English.)

Mo, W, Mb and Ta sheets are widely used as substrates for diamond deposition. These metals are carburized on the surface and this reaction influences diamond nucleation. Diamond growth, however, is not influenced since the vapor pressure of the carbides is very low. Polishing powder remaining on the substrate surface after surface treatment as well as the surface roughness influence the diamond nucleation. The substrates were pretreated with various polishing powders (diamond, B4C, SiC, Al2O3) of different grain sizes (1–50 μm). The influences of these pretreatments on subsequent diamond nucleation and deposition were then investigated.

Real surface area of the aluminium electrode in sodium chloride solution

By combining the techniques of electrochemical slow potentiodynamic, AC impedance and atomic force microscopy (AFM), it was shown that the differences in the anodic dissolution rates of Al in 0.5 NaCl solutions as measured experimentally in the potential region between the corrosion and pitting potential, are mainly due to differences in surface roughness of the electrodes used. It was shown that mechanical grinding and polishing of the electrode surface with emery paper (400 grit) and alumina polishing powder (? 0.25 ?m) can produce surfaces differing by a factor of 6 in the roughness factor Ra. By using AFM estimates of the roughness factors a true electrode capacitance of 4.63?C cm-2 and thickness dox ? 2.0 nm for the barrier layer of the surface film was estamited. The outer part of the film is porous, partly as amorphous Al(OH)3, or crystalline bayerite (Al2O3?3H2O).

Changes of the Dispersive and Phase Composition of Cerox Type Polishing Material as a Result of Exploitation and Mechanoactivation

AbstractThe changes of the dispersive and phase composition of a Cerox type polishing material as a result of its exploitation and mechanochemical treatment are studied. A slightly expressed destruction of the solid solution CeO2‐Ln2O3 during the exploitation and mechanoactivation in water suspension (in centrifugal ball mill) is found out. The mechanoactivation models very well the changes of the dispersive composition of the polishing powder as a result of its use. A similarity in the behaviour of the wasted and the mechanoactivated materials is observed in the case of a treatment with HNO3+H2O2 mixture as well.

Diamond nucleation and growth on refractory metals using microwave plasma deposition

Mo, W, Mb and Ta sheets are widely used as substrates for diamond deposition. These metals are carburized on the surface and this reaction influences diamond nucleation. Diamond growth, however, is not influenced since the vapor pressure of the carbides is very low. Polishing powder remaining on the substrate surface after surface treatment as well as the surface roughness influence the diamond nucleation. The substrates were pretreated with various polishing powders (diamond, B 4C, SiC, Al 2O 3) of different grain sizes (1–50 μm). The influences of these pretreatments on subsequent diamond nucleation and deposition were then investigated.

Effect of mechanical polishing on the surface structure of glasses studied by grazing angle neutron reflectometry

Grazing angle neutron reflectometry, optical and mechanical roughness profilometry techniques have been used to study the effects of the polishing operations on the surface of Borkron Schott glass (special borosilicate glass for neutron optics applications) as the polishing tool pressure P and the mean grain size of the polishing powder Φ. The neutron reflectivity investigations have shown that there is formation of a layer at the surface glass substrate. This layer is less dense than the bulk substrate and its thickness is around 60 Å. The optical and mechanical profilometry measurements have shown that both roughness and waviness decrease with P and Φ. All the experimental results show a good correlation between the neutron refractive index, the thickness and the roughness of the surface layer and the waviness of the glass surface with the two mechanical polishing parameters. The previous techniques have been completed by secondary ion mass spectroscopy and atomic force microscopy measurements.

Scanning tunneling microscope investigation of the effects of CdTe substrate preparation on molecular beam epitaxially grown [formula omitted] layers

Because of the small lattice mismatch, CdTe is used as a substrate materials for the molecular beam epitaxial (MBE) growth of CdTe and Hg 1−x Cd x Te . For investigations of its structural surface properties on a nanometer scale, which greatly influence homogeneous growth, a scanning tunneling microscope is well suited. The surface roughness was determined after different surface preparation steps. Mechanically polished samples show a surface roughness of about 1000 Å, caused by the polishing powder. By chemico-mechanical polishing it was possible to reduce roughness to about 60 Å. Typical surface structures with lateral dimensions of up to 200 Å and vertical dimensions of 40 Å remained after etch-polishing. Further, we studied the effect of substrate polishing on the roughness of the MBE grown layers and found a strong correlation between substrate and layer roughness even for thick layers ( > 1 μ m ). The dependence of the growth temperature on the roughness of n-type CdTe layers is under investigation and the first results are presented.

The Dependence of Photoetching n ‐ InP on Surface Preparation and Electrolyte Metal Ion Impurities

Photochemical etching of using an Ar+ laser and dilute phosphoric acid was studied as a function of surface preparation. The samples were prepared by chemical polishing with a 1% bromine‐methanol solution and mechanical polishing with alumina powders. The surfaces were characterized using electron microscopy, photoluminescence, and mechanical stylus profiling. Photoetch rate was found to increase with surface roughness. The variation of photoetch rate with polishing powder size and morphology was due to the increased effective surface area associated with rougher surfaces. Samples with similar effective surface areas had similar photoetch rates irrespective of their surface treatment. Samples photoetched in solutions having a copper concentration molar and samples with gold wire bonded to them had photoetch rates 2–5 times larger than those without copper in solution. Both zinc and magnesium in solution did not enhance photoetch rates.

Scanning tunneling microscope investigation of CdTe substrate surfaces for molecular beam epitaxy

CdTe substrate surfaces used for molecular beam epitaxy (MBE) have been investigated by scanning tunneling microscope (STM). The surface roughness was determined after different surface preparation steps. Mechanically polished samples show a surface roughness of about 1000 Å, caused by the polishing powder. By chemo-mechanical polishing procedures it was possible to reduce the roughness to about 60 Å. Typical surface structures with lateral dimensions of up to 200 Å and vertical dimensions of 40 Å remained after etch-polishing. This roughness was unaffected by sample preheats up to 300°C, but increased significantly above a temperature of 350°C.

Characterizing the Structure of Abrasive Fineparticles

AbstractA new computer‐aided image analysis procedure for characterizing the number and sharpness of potential cutting facets on the profiles of the image of an abrasive fineparticle is described. In the method, the digitized profile is explored by a running chord generating procedure which generates what is described as the facet signature of the profile. This signature can be processed at different threshold levels to recognize facets of the profile having different levels of sharpness as defined by the acute angle of the facet. Several different ways in which data from the procedure could be used to describe a population of polishing powder fineparticles are outlined. The potential use of the new descriptive characterization procedures for following the physical changes in the powder corresponding to the degeneration in performance of a polishing powder during use is outlined. The possible use of the new methodology to describe the health hazards of angular shaped dust fineparticles and flake type fillers (such as mica) in composite material technology is outlined.

Preparation of ceria-based polishing powders from carbonates

Preparation of ceria-based polishing powders from carbonates

Preparation of ceria-based polishing powders from carbonates

The preparation of Ce(IV) oxide-based polishing powders by thermal decomposition of carbonates was studied and the effect of the calcination process conditions on the properties of product was examined. High-grade polishing powders can be produced at calcination temperatures 700–1200°C, the maximum polishing efficiency is achieved by calcining at 1000–1100°C. The observed dependences were interpreted from the standpoint of the present mechanochemical theory of glass polishing.

The Effect of Diamond Powder Grain Size on the Rate of Polishing Diamond Crystallographic Planes

Summary The polishing process of diamond is based on adhesion wear so the grain size of the diamond polishing powder is important. For each diamond crystallographic plane (facet), there exists an optimum polishing grain size which gives a maximum polishing rate and coefficient of friction Polishing grain size for maximum polishing rate for three different planes is calculated from theoretical considerations and is verified by experimental results.

Use of light scattering to estimate the fraction of spherical particles in a mixture

Two polarization configurations for the light scattered from a mixture of small particles are used to estimate the fraction of spherical particles it contains. The mixture is composed of 0.3-microm alumina polishing powder and 0.106-microm polystyrene spheres. The alumina is an ensemble of randomly oriented irregularly shaped particles. The fraction of spheres in the scattering volume is varied and compared with that deduced from the optical information.

Tribological properties of metal/carbon coatings

Dimigen and Hübsch discovered that carbon‐rich metal/carbon coatings that are deposited with a process combining reactive magnetron sputtering with plasma activated chemical vapor deposition show promising tribological properties. We investigated some of these for metal/carbon compounds of chromium, tungsten, and titanium of different stoichiometry. Friction coefficients against high‐carbon low‐alloy steel were measured in a three pin‐on‐disk configuration. Three‐body wear resistance was evaluated using a modification of the three pin‐on‐disk equipment, where a polishing powder suspension was fed continuously into the tribocontact. The results showed a strong dependence of the tribological properties on composition. The variation in the three‐body wear resistance of tungsten carbon compounds agreed with Rabinowicz’s model for the dependence on Vickers hardness.

Observation of increase in Raman intensity of surface phonon polaritons on rough surfaces of ZnTe

An increase in Raman intensity of surface phonon polaritons has been observed in free-standing thin slabs (thickness ∼ 7 μm) of single- crystal ZnTe with rough surfaces by a conventional Raman-scattering technique at room temperature. The samples with various root-mean- square roughness heights have been prepared by making use of final polishing powders with different mean-grit sizes, and the surface roughness has been confirmed by measuring the intensities of the diffuse scattering of the laser light. The increase of the Raman intensity is proportional to the mean-square height of the surface roughness, and the shift of the dispersion relation is also proportional to it. The frequency shift is explained by a perturbation theory of the surface-roughness-induced scattering.

The polishing of diamond and diamond composite materials

Measurements were made of the rates of removal of material when diamond and diamond composites are polished on a cast iron scaife charged with diamond powder, and on a polishing wheel in which diamond powder is bonded into a metal matrix. Consistent and reproducible values are obtained provided that the cast iron scaife is kept adequately charged with diamond powder. Composite material may then be polished faster than single-crystal diamond, even though many of the diamond crystallites present themselves in unfavourable directions for polish. This relatively high removal rate appears to arise because the polishing powder may sink into the binder of the composite and abrade the edges of the diamond crystallites as well as their surface. The experiments also show that the rate of polish of diamond depends on the degree of subsurface damage produced by previous polishing, and that the cracking and polishing of diamond at low speed is aided by the presence of an atmosphere of air.