Method of producing homogeneous multicomponent dispersions and products derived from such dispersions
A process for producing a dispersion of at least two types of finely divided particles. The process comprises providing at least a first type and a second type of finely divided particles with opposite surface charges and particle sizes which differ by a factor of at least three, and combining the particles and a dispersion medium and forming a substantially homogeneous dispersion of the at least two types of finely divided particles.
1 . A process for producing a dispersion of at least two types of finely divided particles, the process comprising:
(a) providing at least a first type and a second type of the at least two types of finely divided particles, the at least first and second types of particles having opposite surface charges and particle sizes which differ by a factor of at least three;
(b) combining the particles and a dispersion medium and forming a substantially homogeneous dispersion of the at least two types of finely divided particles.
2 . The process of claim 1 , wherein only the first and second types of particles are present.
3 . The process of claim 1 , wherein more than two types of particles are present.
4 . The process of claim 1 , wherein the dispersion medium comprises an aqueous medium.
5 . The process of claim 1 , wherein the dispersion medium comprises an organic medium.
6 . The process of claim 1 , wherein the dispersion medium comprises a mixed aqueous/organic medium.
7 . The process of claim 1 , where the particles comprise solid particles of inorganic origin.
8 . The process of claim 1 , where the particles comprise solid particles of metallic origin.
9 . The process of claim 1 , wherein the particles comprise carbon particles.
10 . The process of claim 1 , wherein the particles comprise particles of substances which are usable in the production of ceramic materials.
11 . The process of claim 1 , wherein the particles comprise one or more particles of at least one of Si, B, Al, Ti, Zr, W, Mo, Cr and Zn, and oxides, mixed oxides, hydrated oxides, nitrides, carbides, suicides, borides, and carbonitrides thereof.
12 . The process of claim 11 , wherein the particles comprise at least one of Al 2 O 3 , TiN and SiC.
13 . The process of claim 1 wherein the particles comprise particles having a size of from 0.1 nm to 10 μm.
14 . The process of claim 13 , wherein at least one of the types of particles has a mean particle size not exceeding 100 nm.
15 . The process of claim 12 , wherein at least one of the types of particles has a mean particle size not exceeding 50 nm.
16 . The process of claim 15 , wherein at least one of the types of particles has a mean particle size not exceeding 30 nm.
17 . The process of claim 13 , wherein the at least first and second types of particles have particle sizes which differ by a factor of at least five.
18 . The process of claim 1 , wherein the at least first and second types of particles have particle sizes which differ by a factor of at least ten.
19 . The process of claim 1 , where the process comprises dispersing at least two types of particles in separate media to form separate dispersions and combining the thus-formed separate dispersions to form the substantially homogeneous dispersion of the at least two types of particles.
20 . The process of claim 19 , where pH values of the separate dispersions are selected such that both in the separate dispersions and in the substantially homogeneous dispersion zeta potentials of the at least two types of particles have different signs.
21 . The process of claim 1 , wherein at least one of the first and second types of finely divided particles are surface-modified to provide first and second types of particles having opposite surface charges.
22 . The process of claim 1 , wherein charged surface groups of at least one of the first and second types of finely divided particles are reacted with a species which provides different charged surface groups.
23 . The process of claim 1 , wherein the process further comprises:
(c) removing the dispersion medium from the dispersion to produce a mixture of particles which is substantially free of the dispersion medium.
24 . The process of claim 23 , wherein the process further comprises:
(d) at least one of washing, drying, and calcining the thus-formed mixture of particles.
25 . A process for producing a dispersion of at least two types of finely divided particles, the process comprising:
(a) providing at least a first type and a second type of the at least two types of finely divided particles, the at least first and second types of particles having opposite surface charges and particle sizes which differ by a factor of at least five;
(b) combining the particles and a dispersion medium and forming a substantially homogeneous dispersion of the at least two types of finely divided particles;
wherein at least one of the types of particles has a mean particle size not exceeding 100 nm and the particles comprise one or more particles of at least one of carbon, Si, B, Al, Ti, Zr, W, Mo, Cr and Zn, and oxides, mixed oxides, hydrated oxides, nitrides, carbides, silicides, borides, and carbonitrides thereof.
26 . A substantially homogeneous dispersion of at least two types of finely divided particles, wherein the dispersion is obtainable by the process of claim 1 .
27 . A substantially homogeneous dispersion of at least two types of finely divided particles, wherein the dispersion comprises a liquid dispersion medium and at least a first type and a second type of the at least two types of finely divided particles, the at least first and second types of particles having opposite surface charges and particle sizes which differ by a factor of at least three.
28 . The dispersion of claim 27 , wherein zeta potentials of the at least two types of particles have different signs.
29 . The dispersion of claim 27 , wherein the particles comprise particles having a size of from 0.1 nm to 10 μm.
30 . The dispersion of claim 29 , wherein at least one of the types of particles has a mean particle size not exceeding 100 nm.
31 . The dispersion of claim 27 , wherein at least one of the types of particles has a mean particle size not exceeding 50 nm.
32 . The dispersion of claim 27 , wherein the at least first and second types of particles have particle sizes which differ by a factor of at least five.
33 . The dispersion of claim 30 , wherein the at least first and second types of particles have particle sizes which differ by a factor of at least ten.