| 摘要 |
A method for increasing density of a region of a porous, phenolic bonded (“PPB”) body adjacent to a selected surface to increase failure tensile strength of the adjacent region and/or to decrease surface recession at elevated temperatures. When the surface-densified PPB body is brought together with a substrate, having a higher failure tensile strength, to form a composite body with a PPB body/substrate interface, the location of tensile failure is moved to a location spaced apart from the interface, the failure tensile strength of the PPB body is increased, and surface recession of the material at elevated temperature is reduced. The method deposits and allows diffusion of a phenolic substance on the selected surface. The PPB body and the substrate may be heated and brought together to form the composite body. The phenolic substance is allowed to diffuse into the PPB body, to volatilize and to cure, to provide a processed body with an increased surface density. |
| 主权项 |
1. A method for modifying density of a surface region of a porous, open cell, phenolic bonded (“PPB”) body to form a surface-densified PPB body, the method comprising:
(1) providing a substrate, having first and second surfaces that are spaced apart by more than 20 mm, where the substrate is a PPB body having a selected temperature T1=20-80° C.; (2) depositing, on the first surface of the substrate, a selected deposited substance comprising a selected phenolic and a selected solvent and a selected resin-to-volume ratio Vr/s, at a deposit temperature T2≈20-80° C., and allowing the deposited substance to diffuse into the PPB body a distance no more than about 20 mm from the first surface; (3) allowing the PPB body to dry for a drying time interval of length Δt3≈6-48 hours at a drying temperature T3≈20-90° C., to allow at least a portion of the solvent to volatilize; (4) allowing the PPB body to set at a curing temperature T4≈60-90° C. for a curing time interval of length Δt4≈6-24 hours; (5) allowing the PPB body to set at a supplemental curing temperature T5≈100-150° C. for a supplemental curing time interval of length Δt5≈3-12 hours, after completion of the curing time interval, to form a surface-densified PPB body, having an undensified-densified interface UDI within the PPB body that is spaced apart from the first surface and spaced apart from the second surface, where a first region of the PPB body, lying on a first side of the UDI and including the first surface, has a majority of the deposited substance, and a second region of the PPB body, lying on a second side of the UDI and including the second surface, has approximately none of the deposited substance; (6) whereby, when the surface-densified PPB body is bonded to a stress isolation pad (SIP) at an interface with the first surface, to form a composite body, one or more of the quantities, T1, T2, T3, T4, T5, Δt3, Δt4, Δt5, the phenolic, the solvent and the ratio Vr/s, can be chosen so that, when a tensile failure test is performed on the composite body using the SIP, failure of the composite body occurs, if at all, at a location within the second region and spaced apart from the UDI. |
