Slurry Formulation Research Articles

Preparation of the Pb(Mg 1/3Nb 2/3)O 3 films by aqueous tape casting

Lead magnesium niobate (PMN) is a relaxor ferroelectric material. Because of its high dielectric constant and superior electrostrictive properties it is commonly used in the manufacture of multilayer electronic devices which is typically produced by tape casting. However, preparation of PMN slurry formulations to use in aqueous tape casting process is not investigated in detail yet. Therefore, in this study aqueous PMN formulations were developed for tape casting and its relation with the final properties of PMN films were investigated. The slurries were prepared using poly(acrylic acid)-based comb polymer as the dispersant, nonionic acrylic latex as the binder and the hydroxypropyl methyl cellulose as the wetting agent. The results showed that it is possible to prepare flexible, crack-free PMN films using highly concentrated suspensions without using any plasticizer. The study gives guidelines for the aqueous tape casting of PMN and can be adapted to processing of other multi-component metal oxides.

Characterization and Use of Quinones as Selective Oxidizers of Tantalum in CMP Applications

The reversible oxidation–reduction reaction of 9,10-anthraquinone-1,8-disulfonic acid potassium salt (1,8-AQDSA-K) was characterized using mass spectrometry and UV-visible spectrophotometry. Quinone derivatives such as anthroquinone disulfonic acid (AQDSA) or its salts were found to promote selective oxidation of tantalum in chemical mechanical planarization when used in slurry formulations. In general, additives with a redox potential between tantalum and copper resulted in a high selectivity of tantalum to copper removal in barrier applications. The details of representative redox reactions and kinetics are presented for AQDSA.

EIS Studies of Copper Dissolution in Arginine and Hydrogen Peroxide

Anodic dissolution of copper in arginine and hydrogen peroxide based medium suitable for chemical mechanical planarization (CMP) slurry formulation was investigated using Electrochemical Impedance Spectroscopy (EIS). Potentiodynamic polarization and impedance data were acquired for copper dissolving in hydrogen peroxide and arginine. Reaction Mechanism Analysis (RMA) was employed to determine the mechanistic pathway of copper dissolution. The results indicate that there is no stable passivating film formation on the copper surface and direct dissolution was also ruled out. A two step mechanism involving cupric oxide as an intermediate species was proposed. The simulated data for this mechanism captures the essential features of the impedance spectra at various overpotentials.

Deposition process of slurry iron aluminide coatings

Diffusion iron aluminide coatings prevent steam oxidation of ferritic/austenitic steels at 650°C for at least 45,000 h. These coatings are deposited by applying Al slurries followed by a diffusion heat treatment at 650°C. The quality of the coatings is very sensitive to a number of factors such as surface preparation, slurry composition and diffusion treatment temperature. A study of the effect of the different processing parameters has been performed in order to optimize the process from an industrial perspective. Moreover, most commercially available Al slurries contain different levels of Cr6+, a highly carcinogenic species, and therefore Cr6+ free slurry formulations have been prepared. In addition, re-coating after exposure has also been developed since it is not clear yet if these coatings will last the 100,000 h which is the life limit for steam power plant design. Based on these studies, processes suitable for coating real size components and re-coating steam exposed components have been developed and are presented in this contribution.

Semi-interpenetrating Polymer Networks Containing Polysaccharides. I Xanthan/Lignin Networks

The polysaccharides are important materials in food, pharmaceutical, cosmetic and related biomedical applications. Xanthan gum is a microbial polysaccharide of great commercial significance. It is well known as one of the best thickening polymers due to its high intrinsic stiffness related to the helical conformation stabilized in the presence of excess salt. It is used in a wide variety of foods for a number of important reasons, including emulsion stabilization, temperature stability, compatibility with food ingredients, and its pseudoplastic rheological properties. Due to its properties in thickening aqueous solutions, as a dispersing agent, and stabilizer of emulsions and suspensions, xanthan gum is used in pharmaceutical formulations, cosmetics, and agricultural products, as well as in textile printing pastes, ceramic glazes, slurry explosive formulations, and rust removers. In this work the crosslinking of a mixture of xanthan and lignins in the presence of the epichlorohydrin, leading to superabsorbant hydrogels with high swelling rate in aqueous mediums, was studied. The swelling properties of these composite hydrogels were investigated. Three different types of lignin have been used namely: aspen wood lignin (L), annual fiber crop lignin (GL) and lignin epoxy-modified resin (LER). Semi-interpenetrating polymer network hydrogels in various ratios were prepared. The influence of gravimetric ratio between components of the semi-interpenetrating polymer networks, as well as the kinetics of water sorption will be discussed. The maximum swelling degree of the hydrogels and the swelling rate constant were determined as a function of the hydrogel's composition. It has been established that the nature of lignin significantly influences swelling process, the chemical modified lignin having a particular behavior.

Applications of a laser assisted defect detection system for chemical mechanical planarization (CMP) slurry development in rigid disk polishing

A laser assisted optical surface analyser (OSA) was applied for inspecting scratch defects on rigid disks used for hard disk drives (HDDs). The disk samples were polished with a chemical mechanical planarization (CMP) technique beforehand. Since it has been recognized that the CMP slurry formulation highly affects the scratch performance of rigid disks, a reliable defect evaluation system is required for efficient slurry development. In this paper, the capability of the OSA tool (Candela C10, KLA-Tencor Corp.) for scratch evaluation is discussed with reference to the scratch data acquired with a conventional dark field microscope (DFM) technique. A gauge repeatability and reproducibility (R&R) study revealed that the Candela had more than three times better R&R performance than the DFM. Scratch counts measured using the two tools were correlated, but not matched, due to the differences in the detection systems. The linear regression correlation coefficient (R2) was found to be 71% for the relatively larger size (>1 mm) of scratch categories. Another study was conducted using a scratch control additive in CMP slurry. The results showed that the effect of the additive was readily detected by the Candela, but was not obvious for the DFM detection. Based on the findings, the similarities and differences of the Candela and the DFM techniques are discussed. It was also found that the tuning capability of the Candela analysis recipe allowed consistent scratch counts with another type of laser assisted defect evaluation tool. This flexibility of the Candela system is a main characteristic which can be effectively used for CMP slurry development. An approach to targeted slurry designs is suggested in conjunction with the advantages and opportunities of the Candela method.

Aqueous tape casting of 10 mol%-Gd 2O 3-doped CeO 2 nano-particles

The aqueous tape casting process was systematically developed and investigated for the tape casting of 10 mol%-Gd 2O 3-doped CeO 2 nano-particles. This study focused on obtaining the optimum slurry formulations and on the effects of the processing parameters such as the stability, the rheology and the wetting properties on the tape characteristics. High solid loading (55 vol.%) and stable slurries of 10GDC nano-particles were achieved using poly(acrylic acid) (PAA) as a dispersant; poly(vinyl alcohol) (PVA) as a binder; poly(ethylene glycol) (PEG) as a plasticizer; octanol as a defoamer and 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate as a surfactant. The pH values of the slurries were maintained in the range of 9.0–10.0. Homogeneous, defect-free green tapes (thickness 150–200 μm) with smooth surface and high relative green density (51.5%) were thus successfully obtained.

New Ultralightweight-Cementing Technology Combines Benefits of Current Leading Methods

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 92970, "New Ultra-Lightweight-Cementing Technology Proven With Case Studies, Combines Benefits of Current Leading Methodologies," by D. Kulakofsky, SPE, O. Araujo, SPE, and F. Self, SPE, Halliburton; A. Mora, Petroleos Mexicanos; and P. Hendriks and P. de Mestre, Petroleum Development Oman, prepared for the 2005 SPE 14th Middle East Oil & Gas Show and Conference, Bahrain, 12–15 March. Historically, the industry has either foamed base cement with nitrogen or added microspheres to the slurry to create ultralight cement slurries. While both of these technologies are considered premium solutions and have been used successfully for a number of years, they each have distinct advantages and limitations when compared to one another. While each is ideal for certain situations, neither one can be used to cover the ever-increasing spectrum of challenges. Lightweight Cement Slurries There are three ways to make lightweight cement, by adding water or microspheres, or by creating a foam. The first method, addition of extra water, while the most common method for creating lightweight cements, cannot be used to create an ultralightweight cement. If water alone is used to reduce the density, the amount of water required to create an ultralight cement will dilute the cement so much that the cement will not solidify in a short period of time. This makes addition of microspheres or foaming the only two lightweight-cementing methods capable of generating a useful oilfield ultralight-weight cement. By use of microspheres, cement-slurry densities have been reduced to 9 and 10 lbm/gal. Case histories are available in which microsphere-containing slurries with densities as low as 7.5 and 8.5 lbm/gal have been pumped. As the slurry density decreases and micro-sphere concentration increases, cost increases. Foamed cements will set up at any density. Because density reduction is accomplished with a gas that costs less than cement, cement cost decreases with decreasing density. Logistics To be mixed and pumped effectively, lightweight cement slurries require a dedicated engineering effort. When using dry-blended cement (with lightweight solids), strict quality-control procedures must be followed to ensure that the blend is stable and meets programmed requirements. The lightweight components can separate from the cement powder, and often it is not convenient to reblend. When the blend is added to the mix water, if the design is flawed, the lighter components may rise to the surface and it will be difficult to trap them within the slurry matrix. Likewise, when lightweight components are added to the mix water, they also may separate immediately and the slurry blend is not re-established easily. Advantages and Limitations As with all slurry formulations, sometimes there must be a compromise in final slurry properties to meet specific objectives. With lightweight slurries, often there is less cement in the mixture and there are higher water/cement ratios. Because of this, the set cement can have a lower compressive strength. A high water/cement ratio can lead to slurry instability and excess free water. High water/cement-ratio cement slurries typically take longer to develop strength and can be susceptible to gas/fluid channeling. Permeabilities of the resulting set-cement column typically are higher than those of conventional slurries.

Corrosion and Inhibition of WNXCY Barrier during Chemical Mechanical Planarization

We investigated the mechanism of chemical and galvanic corrosion of tungsten nitride carbide barrier during Cu chemical mechanical planarization (CMP). Our results demonstrate that chemical corrosion is caused by the oxidation of tungsten (W) in the film by followed by the dissolution of a tungsten oxide complex, which leads to loss. loss is enhanced during CMP due to galvanic corrosion driven by the couple. A high loss rate occurs due to the strong potential difference between Cu and in -containing slurries. A model representing loss in Cu damascene lines during the CMP process is proposed. It supports loss in the top part of the trench sidewall at the interface with Cu. We demonstrate that the use of instead of as the oxidizer, in the formulation of the corrosion-inhibiting model slurries reduces chemical and galvanic corrosion of . Addition of monosaccharides or organic acids prevents excessive Cu loss. Wafer-level tests done with in-house corrosion-inhibiting model slurries show promising Cu and compatibility without significant loss.

Water-based technique to produce porous PZT materials

Water based colloidal processing of PZT materials was investigated in order to reduce costs and employ more environmental friendly manufacturing. The technique addressed was the production of porous thick samples by the so called starch consolidation. PZT soft compositions were used. The starch consolidation process allows to obtain the green body by raising the temperature of a suspension of PZT powder, soluble starch and water, cast into a metal mould. The influence of the processing parameters and composition on the morphology, pore volumes, pore size distributions and piezoelectric properties are investigated. Zeta potential determination and titration with different deflocculants were essential tools to adjust the slurry formulation.

On Raising the Corrosion Stability of Cement Stone

A water - paraffin slurry formulation was elaborated and sedimentation-stable cement mortars with low filter output were obtained on its basis.

Chemical–mechanical polish of aluminum alloy thin films: slurry chemistries and polish mechanisms

This study discusses experimentally the effects of slurry formulation and passivating rate on the chemical mechanical polish removal mechanism of aluminum (Al) alloy films. Two regions of material removal with different slurry pH values, namely, one, non-passivating region (pH<4), and the other, passivating region (pH≥4) are investigated. The removal rates of Al alloy films decline with increasing slurry pH. In the non-passivating region (pH=2) where the material removal is a competition between the passivation and mechanical abrasion plus chemical etching, an optimal removal rate occurs in the slurry with hydrogen peroxide (H2O2) concentration ranging from 0 to 15 vol.%. While the slurry pH is increased to 4 arriving in the passivating region where the material removal is a competition between the passivation and mechanical abrasion only, the material removal has weak dependence to the H2O2 concentration. Too low a slurry, pH results in metal loss and scratching, while too high a slurry, pH leads to oxide residue and insignificant removal rate. Furthermore, removal selectivity and performance of Al/barrier metals and Al/oxide are discussed as well.

Spray-dried ceramic powders: A quantitative correlation between slurry characteristics and shapes of the granules

The characteristics and consequently the properties of ceramic coatings performed using plasma spraying means depend not only on the operating conditions but also on the powder feedstock. Oxide powders are commonly prepared in one stage or in a combination of stages of fusing, crushing, agglomerating and sintering. The spray drying process (which corresponds to the agglomerating route) is a technique in which small constituent particles dispersed in water (which is called slurry) are sprayed in hot air and granulated thanks to a binder (latex or PVA). Spray drying is carried out for a variety of reasons, two major motivations being the production of composite and shape controlled powders for thermal spray applications. The aim of the present work was to establish a correlation between the slurry formulation and the characteristics of the spray dried granules for two oxide ceramics: Al 2 O 3 and Y 2 O 3 –ZrO 2 . Detailed studies on the dispersion and stability of the slurries were performed using sedimentation tests, electrophoretic mobility measurements as well as adsorption isotherms experiments. Then, a drying experimental test based on the drying of a suspended droplet was developed to assess the drying mechanisms, identify the correlation between the slurry characteristics and the morphology of the dried granules and finally to predict the shapes of the spray-dried powders. It was shown that there is a qualitative relation between the sedimentation behaviour (as measured by the sediment ratio) and the granule shape (solid or hollow) and a quantitative relation between the thickness of the shell (for hollow granule) and the state of dispersion and the nature of the binder used. Finally, several powder batches were prepared in the spray-dryer which confirm the reliability of the drying simulation test.

Investigation of the influence of different copper slurry systems on post CMP topography performance

AbstractSince the early days of copper CMP much research and development effort was put into formulation of new copper and barrier CMP slurries. Two major motivations for this effort are the improvement of process performance for currently used integration schemes and the preparation for new integration schemes using low-k and ultra low-k dielectric materials. In this paper a systematic procedure for topography investigation after copper and barrier CMP is presented. The procedure is applied to four different copper slurries in order to compare after copper and after barrier CMP topography performance. As a result of the post copper CMP topography investigations, a discussion of advantages and disadvantages of non-selective and selective barrier polish processes will be presented. To complete the discussion of potential topography correction during barrier CMP, an investigation of an observed pronounced dielectric erosion close to large metal features or within high metal density arrays with medium or high selective barrier CMP processes will be presented.

Tape casting of AlN–SiC–MoSi2 composites

Composites in the system AlN–SiC–MoSi2 were produced by tape casting and sintering. The rheological behaviour of the non-aqueous ceramic suspension was investigated, considering different solvent–deflocculant systems. Slurry formulations were optimised changing the ceramic to total volume ratio and the binder to plasticizer ratio. The characteristics of the green tapes, obtained in different conditions, were studied in terms of apparent density, porosity and microstructure. Sintering tests were carried out under nitrogen atmosphere at temperatures of 1800 and 1850 °C. The density and microstructure of the sintered samples is related to the composition of the tape casting slurries, to the processing procedures and to the sintering conditions. The possibility of tailoring the thickness of the sample by lamination of several tapes has also been evaluated.

A Model of CMP: III. Inhibitors

A model of chemical mechanical polishing (CMP), based on a steady-state balance between chemical growth kinetics for a surface film and its mechanical removal rates, is extended to include the effects of inhibitors on the polishing rate. The general case provides qualitative insights into the process and presents a quantitative measure of inhibitor effectiveness. The model is applied to the case of tungsten CMP, with modifications in some details based on the complexity of the tungsten oxide surface film. The model is used to interpret data for three inhibitors in four slurry formulations and to explain their qualitatively different behaviors. © 2003 The Electrochemical Society. All rights reserved.

Evaluation of a new insecticide formulation (F2) as a protectant of stored wheat, maize, and rice

A new commercial formulation, F2, was evaluated as a protectant of stored wheat, stored maize, and stored rough (paddy) rice. This formulation comprises the technical active ingredients 0.03% deltamethrin, 0.37% piperonyl butoxide, and 0.95% chlorpyriphos-methyl, plus 10% mineral oil and 88.0% of the diatomaceous earth Protect-It ®. Tests were conducted with dust and slurry formulations at 50 and 100 ppm, 57% and 75% relative humidity, and 22°C, 27°C, and 32°C. On wheat, survival of the lesser grain borer, Rhyzopertha dominica (F.), ranged from 0% to 30.0%, survival of the rice weevil, Sitophilus oryzae (L.), was 0–6.2%, and survival of the red flour beetle, Tribolium castaneum (Herbst), was 0–97.5%. Few F 1 adults of any of the three species were found in the treated samples. Survival of the maize weevil, Sitophilus zeamais (Motschulsky), on treated corn was 0–32.5%, while survival of T. castaneum was 0–88.7% in the 50-ppm dust and slurry treatments, and 0–51.4% in the 100-ppm treatments. Again, few F 1 adults of either species were found in treated maize. Survival of R. dominica on treated rough rice averaged 0–4.1% and survival of S. oryzae on treated rice was 0–48.8%, but the majority of weevils that survived were in one replicate. F 1 adults in the treatments ranged from 0 to 24.4. Results show that the combination insecticidal product F2 was extremely effective on all three commodities at the rate of 100 ppm, as either a dust or slurry, and could be used as a commodity protectant.

Effects of PVB on the gelation behavior of BaTiO3-based dielectric particles and glass suspension

Abstract The effect of polyvinyl butyral (PVB) resins on the gelation behavior of the BaTiO 3 -based dielectric particles and borosilicate glass particulate suspensions was investigated in a system where organic solvents, dispersant, binder and gelation modifier were used as processing additives in a low temperature cofired ceramic fabrication processes. The strong flocculation, gels of the suspension without a modifier was attributed to the reaction and strong linkage between the boron in the borosilicate glass and the functional hydroxyl group of PVB resins, which was confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy. When the butyral content of PVB employed in each slurry formulation diminish by approximately 8%, it caused the concentrated suspension to gel. The butyral content of PVB had a much greater impact on gelation than did the molecular weight of PVB. As the molecular weight of PVB was increased, the apparent viscosities of the slurries increased due to the broader chain length of higher molecular weight of PVB. According to the relative viscosity measurement results, both suspensions with high and low PVB molecules had similar viscosity values and it might be regarded as the more viscous feature of PVB polymer solution.

Microstructure of plasma-sprayed titania coatings deposited from spray-dried powder

TiO 2 coatings were prepared by plasma spraying using a spray-dried powder as feedstock material. A systematic study has been performed to determine how the titania slurry formulation (e.g. dispersant level, pH, binder addition) affects the granule characteristics. Aqueous slurries consisting of 50 wt.% of TiO 2 particles, 0–1.2 wt.% ammonium polyacrylate as a dispersant and up to 15 wt.% styrene–ester acrylic copolymer as a binder were investigated using settling experiments. It was shown that when the relative sedimentation height (RSH) value is below 0.45 the fully dispersed slurry leads to the fabrication of a hollow powder whereas when the RSH is over 0.50 the flocculated slurry leads to a dense powder. TiO 2 coatings were prepared from a batch of hollow granules of anatase. The microstructure and crystallographic phases of these deposits were characterised using scanning electron microscopy, three porosimetry methods (image analysis, Archimedean and calculation from thickness and X-ray diffraction, XRD) and quantitative XRD. The results showed that the TiO 2 coatings consist of a mixture of anatase and rutile. The content of anatase was varied from 35 to 50 vol.% depending on the operating conditions (mainly plasma power and cooling rate). These great amounts of anatase phase were obtained along with rather high percentage of porosity (between 13 and 25%).

Alumina slurry formulation intender for spray‐dried powder production

AbstractCeramic powders are used to produce coatings using plasma spray processes. The powder granules are required to have a spherical shape, a mean diameter around 40 µm and, moreover, different densities of the powder must be possible. Alumina powders are obtained by spray drying of concentrated aqueous suspensions of particles (slurries). The suspension must contain high solids loading, be stable during the process and have a relatively low viscosity. The aim of this study was to determine how the properties of aqueous alumina slurries influence the characteristics of granules produced by spray drying. The effects of pH and additives (dispersant and binder) on settling and rheological properties of the alumina slurries were investigated. The curves recorded followed the Casson model in the observed range of shear rate. The Casson yield stress values, τc, and the viscosity values, η were determined and used to evaluate particles interaction in the slurries. The dependence of the yield stress and viscosity was measured as a function of polyacrylate dispersant and binder concentration at pH 4 and 9. The corresponding powders have been characterized on a morphological basis.© 2003 Society of Chemical Industry