Process for producing honeycomb bodies for thermal regenerators
A process for producing a honeycomb body from a noncatalytically active ceramic material for thermal regenerators, comprising the steps of (a) providing a block-shaped monolithic honeycomb body created by extrusion that includes in its interior longitudinal channels; (b) applying a thermal pretreatment to the honeycomb body; (c) after step (b), coating or masking the outer walls of the honeycomb body with a glaze-repellent coating, coating all the longitudinal channels of the honeycomb body with a glaze, and then drying the honeycomb body; and (d) after step (c), performing a firing operation at a temperature typical for the glazed material.
1. A process for producing a honeycomb body from a noncatalytically active ceramic material for thermal regenerators, the process comprising the steps of:
(a) providing a block-shaped monolithic honeycomb body created by extrusion, the honeycomb body having an interior formed with longitudinal channels;
(b) applying a thermal pretreatment to the honeycomb body, whereby the honeycomb body includes surface pores;
(c) after step (b), applying a glaze-repellent coating to outer walls of the honeycomb body, coating a glaze to all the longitudinal channels of the honeycomb body, and then drying the honeycomb body; and
(d) after step (c), performing a firing operation to the glaze to anchor the glaze in the surface pores,
wherein the glaze comprises 65% SiO 2 , 11% Al 2 O 3 , 1% Fe 2 O 3 , 6% CaO, 2% MgO, 2% Na 2 O, 3% K 2 O, 9% ZrO 2 , and 1% Cr 2 O 3 .
2. The process as claimed in claim 1 , wherein the coating of the longitudinal channels is effected in an immersion or flushing process.
3. The process as claimed in claim 1 , wherein the thermal pretreatment comprises a prefiring operation.
4. The process as claimed in claim 1 , wherein the glaze is applied to by spraying or powder-coating.
5. The process as claimed in claim 1 , wherein the step of applying a glaze-repellent coating to outer walls of the honeycomb body is carried out by coating.
6. The process as claimed in claim 1 , wherein the step of applying a glaze-repellent coating to outer walls of the honeycomb body is carried out to form a mask of the glaze-repellent coating on the outer walls of the honeycomb body.
7. The process as claimed in claim 1 , wherein the honeycomb body comprises alumina porcelain or cordierite ceramics.
8. The process as claimed in claim 3 , wherein the longitudinal channels of the honeycomb body intersect with one another forming one or more intersecting points and wherein the open porosity is formed at the one or more intersecting points.
9. The process as claimed in claim 8 , wherein the firing operation is performed to anchor the glaze in the surface pores at the one or more intersecting points.
10. The process as claimed in claim 1 , wherein the outer walls of the honeycomb body are free of the glaze.
11. The process as claimed in claim 1 , wherein the thermal pretreatment is carried out at a temperature lower than a temperature of the firing operation.
12. The process as claimed in claim 1 , wherein the thermal pretreatment is carried out at a temperature of about 900° C.
13. The process as claimed in claim 1 , wherein the firing operation is carried out at a temperature of about 1300° C.
14. The process as claimed in claim 1 , wherein the drying step is carried out at a temperature of about 60° C.
15. A process for producing a honeycomb body from a noncatalytically active ceramic material for thermal regenerators, the process comprising the steps of:
(a) providing a block-shaped monolithic honeycomb body created by extrusion, the honeycomb body having an interior formed with longitudinal channels;
(b) applying a thermal pretreatment to the honeycomb body;
(c) after step (b), applying a glaze-repellent coating to outer walls of the honeycomb body, coating a glaze to all the longitudinal channels of the honeycomb body, and then drying the honeycomb body; and
(d) after step (c), performing a firing operation to the glaze;
wherein the glaze comprises 65% SiO 2 , 11% Al 2 O 3 , 1% Fe 2 O 3 , 6% CaO, 2% MgO, 2% Na 2 O, 3% K 2 O, 9% ZrO 2 , and 1% Cr 2 O 3 .
16. A process for producing a honeycomb body from a noncatalytically active ceramic material for thermal regenerators, the process comprising the steps of:
(a) providing a block-shaped monolithic honeycomb body created by extrusion, the honeycomb body having an interior formed with longitudinal channels, which intersect with one another forming one or more intersecting points;
(b) applying a thermal pretreatment to the honeycomb body, the thermal pretreatment comprising a prefiring operation, whereby the honeycomb body includes open porosity at the one or more intersecting points;
(c) after step (b), applying a glaze-repellent coating to outer walls of the honeycomb body, coating a glaze to all the longitudinal channels of the honeycomb body, and then drying the honeycomb body; and
(d) after step (c), performing a firing operation to the glaze to anchor the glaze in the open porosity in the honeycomb body,
wherein the glaze comprises 65% SiO 2 , 11% Al 2 O 3 , 1% Fe 2 O 3 , 6% CaO, 2% MgO, 2% Na 2 O, 3% K 2 O, 9% ZrO 2 , and 1% Cr 2 O 3 .