Evaluation of Sintering of Nanometer-Sized Titania Using Aerosol Method

The sintering of titania agglomerates consisting of nanometer primary particles in a heated gas flow is investigated under gas temperatures from room temperature to 1673 K. The test titania agglomerates are produced by thermal decomposition or hydrolysis of TTIP (titanium tetraisopropoxide) vapor. The size changes of the agglomerates of 30–100 nm in diameter are measured using a TDMA (Tandem Differential Mobility Analyzer) system. At a temperature lower than about 1000 K, the agglomerates do not change in size with increasing heating temperature, but a sudden decrease in size is detected at 1000 to 1500 K. From TEM observation, densification of agglomerates accompanying primary particle growth is observed. These experimental results for the rate of reduction in surface area are explained quantitatively by solving the basic equation of sintering under the calculated temperature profile.

[1]  R. Averback,et al.  Sintering characteristics of nanocrystalline TiO_2 , 1990 .

[2]  R. German,et al.  Surface Area Reduction During Isothermal Sintering , 1976 .

[3]  T. Seto,et al.  SIZE CHANGE OF VERY FINE SILVER AGGLOMERATES BY SINTERING IN A HEATED FLOW , 1994 .

[4]  Katsuki Kusakabe,et al.  Growth and transformation of TiO2 crystallites in aerosol reactor , 1991 .

[5]  S. Patankar.  Numerical Heat Transfer and Fluid Flow , 2018, Lecture Notes in Mechanical Engineering.

[6]  W. Koch,et al.  The effect of particle coalescence on the surface area of a coagulating aerosol , 1990 .

[7]  Richard W. Siegel,et al.  Synthesis, characterization, and properties of nanophase TiO_2 , 1988 .

[8]  M. Astier,et al.  Determination of the diffusion coefficients from sintering data of ultrafine oxide particles , 1976 .

[9]  D. Rader,et al.  Evaporation rates of monodisperse organic aerosols in the 0.02- to 0.2-μm-diameter range , 1987 .

[10]  T. Gupta,et al.  Sintering of ZnO: I, Densification and Grain Growth , 1968 .

[11]  K. Okuyama,et al.  Determination of particle size distribution of ultra-fine aerosols using a differential mobility analyzer , 1985 .

[12]  T. Seto,et al.  Wall Deposition of Ultrafine Aerosol Particles by Thermophoresis in Nonisothermal Laminar Pipe Flow of Different Carrier Gas , 1994 .

[13]  D. Whitmore,et al.  Kinetics of Initial Sintering of Vacuum‐Reduced Titanium Dioxide , 1962 .

[14]  A. M. Glaeser,et al.  Role of Particle Substructure in the Sintering of Monosized Titania , 1988 .

[15]  J. Seinfeld,et al.  Particle generation in a chemical vapor deposition process with seed particles , 1990 .

[16]  G. D. Ulrich,et al.  III. Coalescence as a Rate-Controlling Process , 1977 .

[17]  Sotiris E. Pratsinis,et al.  Vapor synthesis of titania powder by titanium tetrachloride oxidation , 1991 .

[18]  Harlan U. Anderson,et al.  Initial Sintering of Rutile , 1967 .

[19]  D. A. Venkatu,et al.  Diffusion of titanium of single crystal rutile , 1970 .

[20]  R. L. Coble,et al.  Sintering Crystalline Solids. I. Intermediate and Final State Diffusion Models , 1961 .

[21]  Michael F. Ashby,et al.  A first report on sintering diagrams , 1973 .

[22]  J. Seinfeld,et al.  Production of ultrafine metal oxide aerosol particles by thermal decomposition of metal alkoxide vapors , 1986 .

[23]  R. Haul,et al.  Sauerstoff-selbstdiffusion in Rutilkristallen , 1965 .

[24]  Y. Moriyoshi,et al.  Kinetics of Initial Sintering with Grain Growth , 1970 .

[25]  Sotiris E. Pratsinis,et al.  Formation of agglomerate particles by coagulation and sintering—Part II. The evolution of the morphology of aerosol-made titania, silica and silica-doped titania powders , 1993 .

[26]  A. Schmidt-ott,et al.  New approaches to in situ characterization of ultrafine agglomerates , 1988 .

[27]  L. C. Jonghe,et al.  Effect of Heating Rate on Sintering and Coarsening , 1991 .