Method of forming a ceramic body

In the method of forming a ceramic body, such as for use as a packing body, a dried array of corrugated layers containing ceramic material is first obtained in a green state. Thereafter, the array is cut, for example using a saw, into a desired shape and, thereafter, fired at a firing temperature sufficient to form the array into a one piece ceramic body. The body may initially be cast in a mold which can be cut to shape prior to the final firing step. Alternatively, individual layers of glass fiber material may be coated with ceramic material and dried into the green state prior to cutting and firing.

This invention relates to a method of forming a ceramic body. More 
particularly, this invention relates to a method of forming a ceramic 
packing. Still more particularly, this invention relates to a ceramic 
packing of interconnected corrugated layers. 
Heretofore, various types of ceramic bodies have been known for use in 
various manners. For example, ceramic bodies have been used as packings 
for mass exchange and heat exchange processes. In addition, ceramic bodies 
have been provided as catalyst carriers in industrial plants such as in 
exhaust stacks for hot corrosive gases or vapors. 
In order to manufacture such ceramic bodies, it has been known to prepare 
discrete layers of ceramic material and to then cut the layers to final 
form, for example, using a saw. After cutting, the individual layers have 
been connected together, for example, by using ceramic or a foreign 
binding material stacked and fired as a whole. However, cutting the 
individual layers to final form is a time-consuming process. Further, if 
the ceramic body were to be used as a packing body in a cylindrical 
column, a problem arises in that the brittle nature of the layers causes 
the brittle material to break off at least at the boundary faces during 
cutting. 
It has also been known, for example, from U.S. patent application Ser. No. 
883,061, filed Jul. 8, 1986, to cast a ceramic body as a whole with 
connection sites integrally connecting the individual layers of the body 
so as to form a one-piece body. In such a method, after filling a mold 
with ceramic material to define individual corrugated layers which are 
interconnected, a firing process is carried out in an essentially 
residue-free combustion and/or gasification of the mold. However, while 
this method provides various advantages, there is a disadvantage in that a 
difficult and elaborate processing of the fired packing bodies into an 
orderly array, especially for columns, is required. 
It has also been known from Swiss Patent 619,202 and U.S. Pat. No. 
4,157,929 to manufacture porous, dimensionally stable, heat-resistant and 
corrosion-resistant plate-like structures of fiber glass or glass fiber 
bundles. In this case, a coating of combustable ceramic material is 
applied to the surface of a glass fiber structure so that during firing, 
the intersections of the glass fibers fuse together while, during the 
firing process, a ceramic shell forms to provide a supporting skeletal 
structure. Individual layers may be separately fired and thereafter placed 
in stacked array on each other to form a packing body or several layers 
may be stacked prior to firing so that the individual layers fuse together 
during firing. However, such techniques require time-consuming procedures 
and may also be subjected to breaking off at the boundaries if cutting is 
required. 
Accordingly, it is an object of the invention to provide a cost-efficient 
method for making ceramic bodies. 
It is another object of the invention to reduce the cost of manufacture of 
ceramic bodies. 
It is another object of the invention to simplify the method of making 
ceramic packings. 
Briefly, the invention provides a method of forming a ceramic body wherein 
a dried array of corrugated layers containing ceramic material is first 
obtained in a green state. Thereafter, the array is cut into a 
predetermined shape and thereafter fired at a temperature sufficient to 
form the layers into a one-piece ceramic body. 
By cutting the body to a final shape while in the green state, problems are 
avoided in breaking off the material at the boundaries since the body has 
not yet become brittle. Further, the body can be readily handled in the 
green state for shaping by any suitable means into the desired final 
shape. 
In one embodiment, in order to obtain the green state body, a mold of a 
plurality of layers of material are formed to define a plurality of 
cavities with passages connecting the adjacent cavities. Thereafter, a 
suspension containing ceramic material is introduced into the mold 
cavities and the mold is heated to a temperature sufficient to dry the 
ceramic material into the green state. 
In another embodiment, individual corrugated layers of glass fiber material 
impregnated with a binding substance are stacked together. The stacked 
layers are then immersed in a ceramic solution to form a coating capable 
of being fired thereon. The stacked layers are then dried into a green 
state.

Referring to FIG. 1, in order to perform the method, a mold is formed of 
pairs of layers 1, 2; 3, 4; 5, 6 to define a plurality of cavities 7, 8, 9 
disposed in parallel relation to each other with transverse passages 10 
connecting adjacent cavities. The layers 1-6 may be made of a felting 
screen-shaped (absorbent) cellulose substance, for example cardboard. In 
this respect, the mold may be constructed as described in pending U.S. 
patent application Ser. No. 883,061, filed Jul. 8, 1986. 
The mold is also provided with a filling aperture 11 which communicates 
with at least one of the cavities 7, 8, 9. 
In order to form a ceramic body, the mold is provided with side supporting 
walls (not shown) and a viscous suspension containing a ceramic component 
consisting of kaolin, feltspar, quartz and water, as well as soda is 
poured into the filling aperture 11. During this time, the suspension 
flows through the passages 10 from one layer to another and fills the 
cavities 7, 8, 9 between the layers 1-6. A draining process also takes 
place in which the liquid is withdrawn from the suspension and absorbed by 
the cardboard. 
Thereafter, the mold is placed in a drying oven and dried for approximately 
six hours at approximately 70.degree. C. During this time, the moist air 
is drawn off with the hollow spaces 12 between the pairs of layers 
facilitating removal of the moist air. 
After drying, the dried array of corrugated layers is still supported by 
the layers 1-6 and is in a green state, that is an unfired state. At this 
time, the dried array is cut to final shape, for example, with a belt saw. 
During this time, the layers 1-6 provide sufficient support and necessary 
strength for the filling body to permit the cutting process to be 
performed. The filling body is still in a soft (plastic) state and can, 
therefore, be simply cut to any shape. 
After cutting is completed, the mold layers 1-6 with the filling body is 
placed in an oven and heated to a firing temperature of approximately 
1400.degree. C. and is maintained at this temperature for approximately 
three hours while the combustion gases from the layers 1-6 are drawn off 
and only the finished ceramic body remains. 
Referring to FIG. 2, a ceramic body 20 may be formed of discrete corrugated 
layers 21. In this case, the layers 21 consist of glass fibers, for 
example in the form of glass fiber bundles which have been impregnated 
with a binding substance, for example colloidal silica. In this case, the 
individual layers are dried and given a corrugated shape. Thereafter, the 
corrugated layers are stacked on each other and the so generated filling 
body of stacked layers is immersed in a ceramic solution to form a coating 
capable of being fired. In this respect, the solution may be in the form 
of a sludge with ceramic powder. 
The stacked layers are then dried into a green state and the stacked array 
is then cut to a final shape in an analogous manner to the structure 
described with respect to FIG. 1. 
Thereafter, the shaped layers are fired in a firing oven at a temperature 
sufficient to melt and fuse the glass fiber material in adjacent layers 
together at intersecting points of contact. At the same time, the ceramic 
material forms a skeletal structure over the glass fiber material, for 
example as described in U.S. Pat. No. 4,157,929. 
After the firing process, a porous, dimensional stable, heat and corrosion 
resistant structure is obtained. 
The invention thus provides a method of manufacturing a ceramic body in a 
relatively simple cost-efficient manner. 
Further, the invention permits ceramic bodies to be produced with a desired 
shape, for example for use in packing bodies in material and heat exchange 
columns without great effort.