Dipping solution for use in production of siliceous film and process for producing siliceous film using the dipping solution
View Patent ↗This invention relates to a dipping solution used in a process for producing a siliceous film. The present invention provides a dipping solution and a siliceous film-production process employing the solution. The dipping solution enables to form a homogeneous siliceous film even in concave portions of a substrate having concave portions and convex portions. The substrate is coated with a polysilazane composition, and then dipped in the solution before fire. The dipping solution comprises hydrogen peroxide, a foam-deposit inhibitor, and a solvent.
1. A process for producing a fired siliceous film, comprising;
i) a coating step, in which a substrate surface having concaved portions and convex portions is coated with a composition containing a polysilazane compound,
ii) a dipping step, in which the coated substrate is dipped in a dipping solution comprising hydrogen peroxide, a foam-deposit inhibitor selected from the group consisting of 1 to 20 weight % alcohol, 0.1 to 20 weight % surfactant and a mixture thereof, and a solvent other than said alcohol, wherein the hydrogen peroxide is in the range of 30 to 60 weight % of the total amount of components,
iii) a non-hardening heating step in which the dipped substrate is heated at a temperature lower than that of the hardening step temperature for a shorter time to produce a non-hardened polysilazane film,
iv) a hardening heating step in which the non-hardened polysilazane film is heated at a higher temperature than the non-hardening step for a longer time to convert the non-hardened polysilazane film to a fired siliceous film.
2. The process according to claim 1 for producing a fired siliceous film, wherein the substrate is heated in the hardening step under an inert gas or oxygen gas atmosphere containing steam in a concentration of 1% or more.
3. The process according to claim 1 for producing a fired siliceous film, wherein the substrate is heated in the hardening step at a temperature of 400° C. to 1200° C. for 0.5 to 5 hour.
4. The process according to claim 1 for producing a fired siliceous film, wherein the substrate is heated in the hardening step at a temperature of 400° C. to 1200° C. for 0.5 to 1 hour.
5. The process according to claim 1 for producing a fired siliceous film wherein the dipping solution comprises hydrogen peroxide in the range of 30 to 35 weight % of the total amount of components.
6. The process according to claim 1 for producing a fired siliceous film wherein the polysilazane film is heated in the non-hardening step after dipping at a temperature between 70 and 150° C. for 1 to 10 minutes.
7. The process according to claim 1 for producing a fired siliceous film wherein in the dipping solution said alcohol is 1 to 10 wt %.
8. The process according to claim 7 for producing a fired siliceous film wherein the alcohol in the dipping solution is ethanol.
9. The process according to claim 1 for producing a fired siliceous film wherein the dipping solution comprises 1 to 10 wt % ethanol and the hydrogen peroxide is in the range of 30 to 35 weight % of the total amount of components and further where the preliminarily heating step is 70 and 150° C. for 1 to 10 minutes and the hardening step is done at 400° C. to 1200° C. for 0.5 to 1 hour.