Fresh Slurry Research Articles

Effect of Pad Groove Design on Slurry Injection Scheme during Interlayer Dielectric Chemical Mechanical Planarization

In this study, the effect of pad groove design on slurry injection scheme during interlayer dielectric chemical mechanical planarization was investigated. A novel slurry injection system (SIS) with multiple slurry outlets was designed to allow fresh slurry to be injected through one or multiple points. At first, the SIS with one injection point scheme was compared with the standard slurry application method on a concentrically grooved pad and an xy-groove pad. On the concentrically grooved pad, the SIS with one injection point scheme generated significantly higher oxide removal rates (ranging from 22 to 35 percent) compared to the standard slurry application method at different slurry flow rates. On the xy-groove pad, the SIS with one injection point scheme still resulted in higher removal rates (ranging from 3 to 9 percent), however, its removal rate enhancement was not as high as that of the concentrically grooved pad. In order to further improve slurry availability on the xy-groove pad, SIS with multi-injection point scheme was tested. Results showed that the SIS with multi-injection point scheme resulted in significantly higher removal rates (ranging from 17 to 20 percent) compared to the standard slurry application method. This work underscored the importance of optimum slurry injection scheme for accommodating particular pad groove designs.

Slurry-based additive manufacturing of ceramic parts by selective laser burn-out

Abstract This study proposes a novel process of slurry-based additive manufacturing of ceramic parts by selective laser burn-out (SLB). The process employs the slurry layer to replace the sheet material used in the process of laminated object manufacturing (LOM) and computer-aided manufacturing of laminated engineering materials (CAM-LEM). A part of binder and solution in the fresh slurry layer permeated into the dried green layers to achieve a good binding strength; then the green part was build with laser irradiation to burn out binder. Two scanning modes were used; the outline scanning traced out the outline of the predefined part slice geometry, and cutting scanning facilitated removal of excess material. Consequently, the new process benefits the fabrication of the large parts as LOM and CAM-LEM possessing. Many accessory facilities used in LOM and CAM-LEM are not required. The feasibility of the new process is verified through the fabrication of the alumina parts.

The effects of storage time and temperature on biogas production from dairy cow slurry

The effects of length of storage time and storage temperature on subsequent biogas production from dairy cow slurry by anaerobic digestion were investigated. Slurry was stored under anaerobic conditions at 9 °C and 20 °C for between 1 and 26 weeks prior to digestion. Digestion was carried out in 7 l continuously stirred tank reactors, with an average hydraulic retention time of 25 d. Storage of slurry at 9 °C had no significant effect on subsequent biogas production. However, after 8 weeks of storage at 20 °C there was an increasing negative impact on subsequent biogas production so that after 26 weeks of storage at 20 °C biogas production had decreased from 16.4 m3 t−1 to 5 m3 t−1 of fresh slurry. This reduction was strongly related to the decrease in the concentration of volatile solids in the stored slurry which was approximately 0.4 g kg−1 week−1. Storage time and temperature had no affect on the total nitrogen concentrations in the slurries, though both factors resulted in small increases in ammonia nitrogen concentrations.

Novel Slurry Injection System for Improved Slurry Flow and Reduced Defects in CMP

In commercial CMP tools, slurry is applied near the pad center. As the pad rotates, more than 95% of the fresh slurry flows directly off the surface due to bow wave formation and inertial forces without ever entering the pad-wafer interface, resulting in low slurry utilization [1]. Furthermore, some slurry that manages to go under the wafer stays on the pad, mixes with fresh slurry and re-enters the pad-wafer interface. This used slurry contains reaction products, foam and pad debris (due to pad conditioning) that cause wafer-level defects [2]. Such defect-causing by-products keep recirculating on the pad during polishing and accumulate near the retaining ring over time. Also, since large amounts of DI water are used between wafer polishes to rinse off the debris and reaction products, appreciable amounts of water may stay on the pad and inside the grooves. When fresh slurry is introduced to polish the next wafer, it mixes with the residual water and is diluted, resulting in lower material removal. As such, the current slurry application method does not provide efficient slurry utilization and leaves significant room for improving defect levels. Moreover, the constant sweeping of the conditioner arm during in-situ conditioning results in uneven slurry distribution and introduces additional challenges when it comes to carrier multi-zone pressure control for reduced within-wafer removal rate non-uniformity.

PH-sensitive hydrogels for colon specific delivery

A novel fluid loss additive (FLA) was synthesized using 2-acrylamido-2-methyl-propane sulphonic acid, acrylic acid, N,N-dimethyl acrylamide and N-vinyl-2-pyrrolidone by aqueous solution polymerization. TGA spectrum indicated that the decomposition temperature of FLA was higher than 330°C. The fluid loss testing showed that the FLA had an outstanding property of reducing fluid loss at 203°C in salt water cement slurry and the amount of fluid loss was controlled about 100 mL when FLA dosage was 1.0%. Cement slurry with 0.1–1.5% FLA kept stable thickening time. A better performance of FLA was found in fresh water cement slurry than in salt water cement slurry.

Factor Effect on Material Removal Rate During Phosphate Laser Glass Polishing

In this work, the effects of different process parameters on the material removal rate (MRR) of phosphate laser glass during ring polishing had been investigated. Experiments were performed on a ring polishing machine that had a pad diameter of 4.4 m, and the MRR was obtained by the measurements of depth reduction of a groove on phosphate glass sample. The experimental results and analyses showed that size of the abrasive particles and the ceria concentration had significant effects on the polishing rate. The MRR of glass being polished on the annular-grooved pad was almost three times as when polished on the square-grooved pad. When the pad was periodically cleaned with water and glass was polished with fresh slurry, the value of MRR tended to be constant. Based on the experimental results, a combined process was designed to optimize MRR. The results of this study provided the essential foundation for obtaining the required MRR and optimizing the fabrication technique.

A hydrodynamic and kinematic analysis of chemical–mechanical planarization mechanism in double sided polisher

In this study, a hydrodynamic and kinematic analysis of the double sided chemical–mechanical planarization (CMP) mechanism is discussed. The workpieces are disk substrates with a hole at the center. The hydrodynamic results show that the disk surface has a positive fluid pressure zone and a negative pressure zone. The positive pressure zone squeezes out the used slurry and the negative pressure zone sucks in the fresh slurry. The high pressurized slurry with abrasive particles has a significant interaction with the disk surface and removes the material. The self rotation of the disks inside the carriers is beneficial for the uniformity and global planarization of the disks. The kinematic analysis results show that a transient center of the carriers exists and the velocity magnitude and direction change abruptly at this position. It should be avoided on the disk surface, because such a transient center is a halt point which may cause defects on the disk surface. The velocity at the carrier center is steady, but the velocity at the carrier edge has a larger oscillation with a higher average number. The critical waviness and surface integrity can be optimized via the kinematic parameters by the abrasive particle trajectories on the disk surface.

The Stone Slurry in Palestine from Environmental Burden to Economic Opportunities—Feasibility Analysis

This research will examine the potentially economic, environmental, and political impacts for recycling the stone slurry in Palestine through utilization of this slurry in the ready mix concrete industry. The utilization concept is concluded in incorporation of the stone slurry as a partial replacement of the fine ingredient of the concrete mix which is the natural sand, based on several empirical studies that have proved the possibility for this utilization. The proposed utilization would result in a rather integration between these two main economic sectors: stone industry, and ready mix concrete industry. The results of this research revealed significant economic and environmental gains in terms of money and natural resources saved if partial replacement of natural sand with fresh stone slurry has been adopted.

Chemical mechanical planarization of amorphous Ge2Sb2Te5 with a soft pad

Chemical mechanical planarization (CMP) of amorphous Ge2Sb2Te5 (a-GST) is investigated using two typical soft pads (politex REG and AT) in acidic slurry. After CMP, it is found that the removal rate (RR) of a-GST increases with an increase of runs number for both pads. However, it achieves the higher RR and better surface quality of a-GST for an AT pad. The in-situ sheet resistance (Rs) measure shows the higher Rs of a-GST polishing can be gained after CMP using both pads and the high Rs is beneficial to lower the reset current for the PCM cells. In order to find the root cause of the different RR of a-GST polishing with different pads, the surface morphology and characteristics of both new and used pads are analyzed, it shows that the AT pad has smaller porosity size and more pore counts than that of the REG pad, and thus the AT pad can transport more fresh slurry to the reaction interface between the pad and a-GST, which results in the high RR of a-GST due to enhanced chemical reaction.

Mn2O3 Slurry Achieving Reduction of Slurry Waste

Fumed silica is widely used for SiO2 chemical mechanical polishing (CMP). In semiconductor processes, only fresh slurry is used, the used slurry being disposed of. We have demonstrated that Mn2O3 abrasive slurry polishes dielectric SiO2 film, giving 4 times the removal rate of conventional fumed silica slurry. The higher removal rate reduces the total amount of slurry used, consequently reducing the amount of used slurry waste. The removal rate of Mn2O3 slurry remains constant for solid concentrations between l and 10 wt %, and stays constant without pad conditioning. These characteristics are very useful for slurry reuse. Remanufacture of Mn2O3 slurry from used slurry has been demonstrated, and the removal rates of the remanufactured and fresh slurries are the same. Reuse and remanufacturing drastically reduce the amount of waste.

Mn2O3 Slurry Reuse by Circulation Achieving High Constant Removal Rate

Fumed silica is widely used in SiO2 chemical mechanical polishing (CMP). In semiconductor processes, only fresh slurry is used, and used slurry is disposed. Sustainable development demands a reduction in waste. Since reuse of slurry is effective for reducing the amount of used slurry generated, we investigated the reuse of Mn2O3 slurry and conventional fumed silica slurry. In both cases, abrasive concentration decreases as reuse time increases. The removal rate for Mn2O3 slurry maintains a value 4 times that of the conventional fumed silica slurry during slurry reuse, because the removal rate for Mn2O3 slurry is almost constant for solid concentrations between 1.0 and 10 wt %. Pad conditioning was not performed for Mn2O3 slurry. The removal rate for conventional slurry decreases as the number of times of reuse increases, even when pad conditioning is appropriately performed.

Effect of temperature on survival of micro-organisms and performance of anaerobic two-stage reactors treating cattle slurry

A short-term thermophilic treatment was conducted in order to study the survival of micro-organisms in slurry derived from a cattle farm, at temperatures of 58, 63 and 68°C for 6 h. The second trial was a biogas production experiment with an anaerobic mesophilic first stage and a thermophilic second stage. The mesophilic treatment was at 38°C and the second stage was conducted at 55, 58 or 65°C. The results of first trial showed that survival of micro-organisms was decreased remarkably at higher temperatures in spite of the fact that during the experiment part of slurry was replaced with fresh slurry. Meanwhile, the second trial showed that optimum production of biogas was at 55°C while the best result for hygienic control was achieved at 65°C.

Effects of Cattle Slurry Acidification on Ammonia and Methane Evolution during Storage

Slurry acidification before storage is known to reduce NH(3) emissions, but recent observations have indicated that CH(4) emissions are also reduced. We investigated the evolution of CH(4) from fresh and aged cattle slurry during 3 mo of storage as influenced by pH adjustment to 5.5 with sulfuric acid. In a third storage experiment, cattle slurry acidified with commercial equipment on two farms was incubated. In the manipulation experiments, effects of acid and sulfate were distinguished by adding hydrochloric acid and potassium sulfate separately or in combination, rather than sulfuric acid. In one experiment sulfur was also added to slurry as the amino acid methionine in separate treatments. In each treatment 20-kg portions of slurry (n = 4) were stored for 95 d. All samples were subsampled nine to 10 times for determination of NH(3) and CH(4) evolution rates using a 2-L flow-through system. In all experiments, the pH of acidified cattle slurry increased gradually to between 6.5 and 7. Acidification of slurry reduced the evolution of CH(4) by 67 to 87%. The greatest reduction was observed with aged cattle slurry, which had a much higher potential for CH(4) production than fresh slurry. Sulfate and methionine amendment to cattle slurry without pH adjustment also significantly inhibited methanogenesis, probably as a result of sulfide production. The study suggests that complex microbial interactions involving sulfur transformations and pH determine the potential for CH(4) emission during storage of cattle slurry, and that slurry acidification may be a cost-effective greenhouse gas mitigation option.

Ultrasonic sound speed analysis of hydrating calcium sulphate hemihydrate

This article focuses on the hydration, and associated microstructure development, of β-hemihydrate to dihydrate (gypsum). The sound velocity is used to quantify the composition of the fresh slurry as well as the hardening and hardened—porous—material. Furthermore, an overview of available hydration kinetic and volumetric models for gypsum is addressed. The presented models predict the sound velocity through slurries and hardened products. These states correspond to the starting and ending times of the hydration process. The present research shows that a linear relation between the amount of hydration-product (gypsum) formed and sound velocity (Smith et al., J Eur Ceram Soc 22(12):1947, 2002) can be used to describe this process. To this end, the amount of hydration-product formed is determined using the equations of Schiller (J Appl Chem Biotechnol 24(7):379, 1974) for the hydration process and of Brouwers (A hydration model of Portland cement using the work of Powers and Brownyard, 2011) for the volume fractions of binder, water and hydration products during the hydration process.

Pig feeding strategy coupled with effluent management – fresh or stored slurry, solid phase separation – on methane potential and methane conversion factors during storage

In the guideline for the determination of methane (CH 4 ) emission from animal manure (IPCC) the amount of CH 4 emitted is generally calculated according to an equation combining the amount of organic matter (OM) or volatile solids excreted, the ultimate CH 4 potential ( B 0 ) of excreta and a system-specific methane conversion factor (MCF, %) that reflects the portion of B 0 that is really converted into CH 4 . The objective of the present study was to investigate the effect of the modification of dietary crude protein and fibre levels on B 0 of pig slurry and on subsequent MCF according to different strategies of slurry management. Five experimental diets differing mainly in their crude protein and fibre content were compared. Two types of measurement of CH 4 emission were performed. The first was the measurement of B 0 of slurry using biomethanogene potential (BMP) test. The second consisted in a storage simulation, which was performed on different kinds of effluents: fresh slurry (FSl), stored slurry (SSl), and faeces mixed with water (FaW). The type of diet and the type of effluent affected ( P < 0.001) CH 4 production after 30, 50 and 100 days. Moreover, the interaction between type of effluent and type of diet was significant for CH 4 emission and for MCF. CH 4 production was the highest for BMP, the average production of CH 4 during storage from FaW, FSl and SSl samples representing 77%, 58% and 64% of the B 0 value. The dynamic of CH 4 production during BMP tests was rather similar for all dietary treatments whereas it differed for storage simulation studies with significant effects of dietary CP and fibre contents. The results from this study indicate that the type of diet has a significant but rather limited effect on B 0 value of effluent. The effect of diet is much more marked on MCF, with lower values for high protein diets, and higher values for high fibre diets. MCF is also affected by manure management, the values measured on separated faeces from urine being much higher than for slurry. ► The amount of organic matter and nitrogen excreted per pig is affect by the diet. ► Dynamic of effluent methane production differs according to diet composition. ► Dietary protein and fibre affect methane conversion factor (MCF). ► MCF is also affected by manure management with higher values for separated faeces.

Effect of operational conditions on the degradation of organic matter and development of microalgae–bacteria consortia when treating swine slurry

There is great controversy regarding the best substrate (fresh or anaerobically digested swine slurry) for the development of microalgae-bacteria consortia. This study aims to elucidate the best substrate by assessing biomass productivity, microorganism predominance, and their ability for organic matter removal. In addition to the different substrates, different operational conditions and influent strengths were evaluated. Increasing organic matter content when favourable temperature and illumination conditions were present improved biomass production. However, these conditions were not favourable for microalgal growth, but they were favourable for bacteria. Regardless of the operational conditions, reactors fed with fresh slurry not only resulted in the highest biomass productivity, but also the greatest removal of total and soluble chemical oxygen demand (COD). On the other hand, reactors fed with digested slurry showed biomass productivity and COD removal values lower than those obtained for reactors fed with fresh slurry, most probably due to the recalcitrant nature of the former. Nevertheless, digested slurry was the substrate more appropriate for microalgae growth under harsh operational conditions (16 °C and 9-h illumination) at low influent strength and optimum operational conditions (30 °C and 24-h illumination) at higher influent strength.

Earthworm effects on gaseous emissions during vermifiltration of pig fresh slurry

Treatment of liquid manure can result in the production of ammonia, nitrous oxide and methane. Earthworms mix and transform nitrogen and carbon without consuming additional energy. The objective of this paper is to analyse whether earthworms modify the emissions of NH3, N2O, CH4 and CO2 during vermifiltration of pig slurry.The experiment used mesocosms of around 50L, made from a vermifilter treating the diluted manure of a swine house. Three levels of slurry were added to the mesocosms, with or without earthworms, during one month, in triplicate. Earthworm abundance and gas emissions were measured three and five times, respectively.There was a decrease in emissions of ammonia and nitrous oxide and a sink of methane in treatments with earthworms. We suggest that earthworm abundance can be used as a bioindicator of low energy input, and low greenhouse gas and ammonia output in systems using fresh slurry with water recycling.

Nitrogen transformations under different conditions in open ponds by means of microalgae–bacteria consortium treating pig slurry

Four open ponds inoculated with microalgae-bacteria consortium treating different swine slurries (fresh and anaerobically digested) were evaluated in terms of nitrogen transformation under optimal and real conditions of temperature and illumination. Ammonium complete depletion was not achieved. Ponds operated under real conditions presented lower ammonium removal. Elimination capacities were around 26 mg N/Ld and were subsequently increased with increasing inlet ammonium loading rate. Different nitrogen transformation was observed depending on substrate source. When anaerobically digested slurry was fed to the ponds, nitrification followed by biomass uptake and denitrification were the main nitrogen transformation taking place depending on inlet ammonium loading rate and operational conditions. Ponds fed with fresh slurry exhibited denitrification as the main nitrogen removal mechanism for the pond operated under real conditions while under optimal conditions stripping, denitrification and biomass uptake contributed similarly. Therefore, this study confirmed that the so-claimed nitrogen recovery by microalgae biomass is frequently overestimated.

Serial Repitching of Dried Lager Yeast

To demonstrate the suitability of active dried yeast (ADY) for serial repitching, dried and wet yeast slurries derived from the same strain were analyzed for five consecutive fermentations (G0–G4). In each instance, cell viability was determined prior to pitching, while yeast performance was assessed by analyzing fermentation profiles and the characteristics of the final products. In addition, beers produced using wet and dried G0 and G4 yeast were analyzed and compared for their concentrations of esters and higher alcohols. Yeast obtained at the end of each fermentation was screened for the presence of respiratory-deficient mutants and flocculent variants. Yeast slurries recovered from G4 beer were examined for genetic changes, as characterized by movement of Ty elements and chromosome length polymorphisms. This study shows that serially repitched wet and dried yeasts perform in a similar fashion and that repitched cultures exhibit more typical fermentation and flavor profiles than fresh slurries. In addition, the study demonstrates that the accumulation of genetic and phenotypic variants is not associated with serial repitching of dried yeast cultures. Consequently, it is proposed that ADY can be reused in a similar fashion to wet yeast without any adverse effects on fermentation performance, yeast quality, or flavor production.

A simplified approach to calculate slurry production of growing pigs at farm level

A simplified approach to predict the amount of slurry produced by growing pigs at farm level is proposed. The inputs are initial (LWi) and final (LWf) live weights, production (t) and empty (empty) periods, feed consumption (FC), dry matter (DMD), N digestibilities and farm water consumption per pig (FWC). Estimates of the amount of water required (or arisen) per kg of feed for the various physiological functions were estimated by running a published mathematical model using data representing the ordinary conditions of rearing. Water excretion was estimated in two ways depending on: 1) free access (ad lib) to water; 2) restricted access (forced). In the first case, the proportion of water consumed (wiad lib) and those excreted with the urine (wuad lib) and the faeces (wfec) were quantified to be 2.9, 1.72 and 0.33 kg per kg of feed, respectively. From the urinary excretions of N and minerals, obtained as the difference between the digestible nutrient intakes and the retentions, the model predicted a urinary DM content of 2.1% (by weight). In the second case, for pigs receiving drinking water in forced ratio with the feed (wiforced), the urinary production was calculated as wuforced=(wiforced+wf+wo)-(wd+ws+wg+wfec+we), where wf=water content in feed (0.12 kg/kg), wo=water arising from nutrient oxidation (0.25 kg/kg), wd=water required for digestion (0.08 kg/kg), ws=water demand for protein and lipid synthesis (0.06 kg/kg), wg=water retained in body tissues (0.14 kg/kg) and we=water lost through evaporation (0.96 kg/kg). Estimates of fresh slurry production (faeces+urine) were regressed against the values resulting from empirical literature equations and referred to pigs fed water:feed ratios of 2.5:1, 2.9:1 and 4:1. The resulting regression (R2=0.97), with a slope close to unity (1.05), indicated that the approach can be extended to predict the farm fresh slurry production with pigs having free access to water or kept on different water:feed ratios. In agreement with international literature, but not with the current Italian national standards, estimates of mature slurry productions ranged from 1.5 to 2.9 ton/pig/year with DM contents ranging from 8.3 to 3.7%. At farm level the use water meters is recommended as from FWC minus the estimated water consumption (FWCexp) the farmer can evaluate the extra wastage and adjust the predicted mature slurry production.