The chemical mechanical polishing (CMP) process has become a widely accepted global planarization technology.The abrasive material is one of the key elements in CMP.In the presented paper,an Ag-doped colloidal SiO2 ab...The chemical mechanical polishing (CMP) process has become a widely accepted global planarization technology.The abrasive material is one of the key elements in CMP.In the presented paper,an Ag-doped colloidal SiO2 abrasive is synthesized by a seed-induced growth method.It is characterized by time-of-flight secondary ion mass spectroscopy and scanning electron microscopy to analyze the composition and morphology.The CMP performance of the Ag-doped colloidal silica abrasives on sapphire substrates is investigated.Experiment results show the material removal rate (MRR) of Ag-doped colloidal silica abrasives is obviously higher than that of pure colloidal silica abrasives under the same testing conditions.The surfaces that are polished by composite colloidal abrasives exhibit lower surface roughness (Ra) than those polished by pure colloidal silica abrasives.Furthermore,the acting mechanism of Ag-doped colloidal SiO2 composite abrasives in sapphire CMP is analyzed by X-ray photoelectron spectroscopy,and analytical results show that element Ag forms Ag2O which acts as a catalyst to promote the chemical effect in CMP and leads to the increasing of MRR.展开更多
Colloidal gas aphron(CGA)based fluid has become very popular in drilling in the last two decades,as it reduces formation damages significantly.In this study,sugarcane molasses(Mls)was used for the first time as a poly...Colloidal gas aphron(CGA)based fluid has become very popular in drilling in the last two decades,as it reduces formation damages significantly.In this study,sugarcane molasses(Mls)was used for the first time as a polymer in CGA-based to investigate its ability to improve the role of aphronized fluid as a drilling fluid.The results showed that increasing the concentration of Mls to 12%(v/v)in CGA-based fluid reduces the drainage rate and increases half-life to 10.6 min,resulting in enhanced stability of the aphronized fluid.Also,because of increasing Mls concentration from 1%to 12%(v/v),the yield and the initial gas hold-up decrease to 74%and 299.4 mL,respectively,indicating that the presence of Mls allows less air into the aphron system.Although the rheological properties were improved in this study,the gel strength did not change considerably.Furthermore,the results showed that by increasing the concentration of Mls,the average size of the bubbles decreases,and the particle-size distribution becomes more uniform.Finally,the API filtration test revealed that the higher the Mls concentration in the aphronized fluid,the lower the fluid loss,and at the Mls concentration of 12%(v/v),the fluid loss was estimated at 19.54 mL.A natural polysaccharide with high molecular weight,Mls can be used as a polymer in CGAbased fluid and,thus,improve its performance.展开更多
A kinetic model fitted by the empirical equation has been proposed to describe the liquid drainage behavior. Rate constants （kd） of liquid drainage equation could be obtained from the above empirical equation. In th...A kinetic model fitted by the empirical equation has been proposed to describe the liquid drainage behavior. Rate constants （kd） of liquid drainage equation could be obtained from the above empirical equation. In this paper, the stability of the colloidal gas aphrons （CGAs）, the effect of concentrations of sodium dodecyl benzene sulphate （SDBS）, dodecyl trimethylammonium bromide （HTAB） and polyoxyethylene sorbitol anhydride monolaurate（Tween-20）, temperature, stirring speed, stirring time, and various kinds of salts on the kd of liquid drainage are further investigated. The results show that the Arrhenius equation can be successfully used to describe the relation between kd arid absolute temperature （T）, and concentrations of surfactants, stirring speed, stirring time and salinities also have great effect on the kd. At last, the CGAs drainage mechanism is explained from analysis of the rate of liquid drainage as a function of time.展开更多
The extinction cross sections of a system containing two particles are calculated by the T-matrix method, and the results are compared with those of two single particles with single-scattering approximation. The neces...The extinction cross sections of a system containing two particles are calculated by the T-matrix method, and the results are compared with those of two single particles with single-scattering approximation. The necessity of the correction of the refractive indices of water and polystyrene for different incident wavelengths is particularly addressed in the calculation. By this means, the volume fractions allowed for certain accuracy requirements of single-scattering approximation in the light scattering experiment can be evaluated. The volume fractions calculated with corrected refractive indices are compared with those obtained with fixed refractive indices which have been rather commonly used, showing that fixed refractive indices may cause significant error in evaluating multiple scattering effect. The results also give a simple criterion for selecting the incident wavelength and particle size to avoid the ＇blind zone＇ in the turbidity measurement, where the turbidity change is insensitive to aggregation of two particles.展开更多
基金the National Natural Science Foundation of China
文摘The chemical mechanical polishing (CMP) process has become a widely accepted global planarization technology.The abrasive material is one of the key elements in CMP.In the presented paper,an Ag-doped colloidal SiO2 abrasive is synthesized by a seed-induced growth method.It is characterized by time-of-flight secondary ion mass spectroscopy and scanning electron microscopy to analyze the composition and morphology.The CMP performance of the Ag-doped colloidal silica abrasives on sapphire substrates is investigated.Experiment results show the material removal rate (MRR) of Ag-doped colloidal silica abrasives is obviously higher than that of pure colloidal silica abrasives under the same testing conditions.The surfaces that are polished by composite colloidal abrasives exhibit lower surface roughness (Ra) than those polished by pure colloidal silica abrasives.Furthermore,the acting mechanism of Ag-doped colloidal SiO2 composite abrasives in sapphire CMP is analyzed by X-ray photoelectron spectroscopy,and analytical results show that element Ag forms Ag2O which acts as a catalyst to promote the chemical effect in CMP and leads to the increasing of MRR.
文摘Colloidal gas aphron(CGA)based fluid has become very popular in drilling in the last two decades,as it reduces formation damages significantly.In this study,sugarcane molasses(Mls)was used for the first time as a polymer in CGA-based to investigate its ability to improve the role of aphronized fluid as a drilling fluid.The results showed that increasing the concentration of Mls to 12%(v/v)in CGA-based fluid reduces the drainage rate and increases half-life to 10.6 min,resulting in enhanced stability of the aphronized fluid.Also,because of increasing Mls concentration from 1%to 12%(v/v),the yield and the initial gas hold-up decrease to 74%and 299.4 mL,respectively,indicating that the presence of Mls allows less air into the aphron system.Although the rheological properties were improved in this study,the gel strength did not change considerably.Furthermore,the results showed that by increasing the concentration of Mls,the average size of the bubbles decreases,and the particle-size distribution becomes more uniform.Finally,the API filtration test revealed that the higher the Mls concentration in the aphronized fluid,the lower the fluid loss,and at the Mls concentration of 12%(v/v),the fluid loss was estimated at 19.54 mL.A natural polysaccharide with high molecular weight,Mls can be used as a polymer in CGAbased fluid and,thus,improve its performance.
基金Supported by the Eleventh Five Year National Key Technology R&D Program (2008BAE58B01)New Century Excellent Talents of Ministry of Education (NCET-07-0577),the People’s Republic of China
文摘A kinetic model fitted by the empirical equation has been proposed to describe the liquid drainage behavior. Rate constants （kd） of liquid drainage equation could be obtained from the above empirical equation. In this paper, the stability of the colloidal gas aphrons （CGAs）, the effect of concentrations of sodium dodecyl benzene sulphate （SDBS）, dodecyl trimethylammonium bromide （HTAB） and polyoxyethylene sorbitol anhydride monolaurate（Tween-20）, temperature, stirring speed, stirring time, and various kinds of salts on the kd of liquid drainage are further investigated. The results show that the Arrhenius equation can be successfully used to describe the relation between kd arid absolute temperature （T）, and concentrations of surfactants, stirring speed, stirring time and salinities also have great effect on the kd. At last, the CGAs drainage mechanism is explained from analysis of the rate of liquid drainage as a function of time.
基金Supported by the National Natural Science Foundation of China under Grand Nos 10672173 and 10332050, and the China Postdoctoral Science Foundation.
文摘The extinction cross sections of a system containing two particles are calculated by the T-matrix method, and the results are compared with those of two single particles with single-scattering approximation. The necessity of the correction of the refractive indices of water and polystyrene for different incident wavelengths is particularly addressed in the calculation. By this means, the volume fractions allowed for certain accuracy requirements of single-scattering approximation in the light scattering experiment can be evaluated. The volume fractions calculated with corrected refractive indices are compared with those obtained with fixed refractive indices which have been rather commonly used, showing that fixed refractive indices may cause significant error in evaluating multiple scattering effect. The results also give a simple criterion for selecting the incident wavelength and particle size to avoid the ＇blind zone＇ in the turbidity measurement, where the turbidity change is insensitive to aggregation of two particles.
