High temperature composite honeycomb

A method for making a composite honeycomb that is suitable for use in high temperature environments, said composite honeycomb having a lengthwise direction, a widthwise direction and a thickness direction wherein said composite honeycomb has a length shear strength measured in said lengthwise direction and a width shear strength measured in said widthwise direction, said method comprising the steps of:

• A) providing a honeycomb precursor that comprises:
• a) a plurality of upper corrugated ribbons comprising a first plurality of alternating upper channels and upper nodes, said first plurality extending in said lengthwise direction wherein each of said upper channels and each of said upper nodes extends in said thickness direction and wherein each of said upper corrugated ribbons comprises a first fibrous support having a first fibrous support weight expressed in grams per square centimeter and a first high temperature resin matrix;
• b) a plurality of lower corrugated ribbons comprising a second plurality of alternating lower channels and lower nodes, said second plurality extending in said lengthwise direction, wherein each of said lower channels and each of said lower nodes extends in said thickness direction and wherein each of said lower corrugated ribbons comprises a second fibrous support having a second fibrous support weight expressed in grams per square centimeter and a second high temperature resin matrix, said upper corrugated ribbons and lower corrugated ribbons forming a honeycomb structure comprising alternating layers of upper corrugated ribbons and lower corrugated ribbons that are stacked in said widthwise direction, wherein the channels of said upper corrugated ribbons are bonded to the nodes of said lower corrugated ribbons with a high temperature node adhesive and wherein the channels of said lower corrugated ribbons are bonded to the nodes of said upper corrugated ribbons with a high temperature node adhesive such that a plurality of honeycomb cells are formed wherein each of said honeycomb cells extends in said thickness direction, said honeycomb cells each having a left side and a right side, wherein each of said honeycomb cells is defined by honeycomb cell walls, said honeycomb cell walls comprising a lower wall that extends between said left side and said right side of the honeycomb cell and an upper wall that also extends between said left side and said right side of the honeycomb cell, said lower wall comprising a lower concave left end portion, a lower concave right end portion and a lower central portion located between said lower concave left end portion and said lower concave right end portion, said upper wall comprising an upper convex left end portion, an upper convex right end portion and an upper central portion located between said upper convex left and said upper convex right end portion, wherein said lower concave left end portion and said upper convex left end portion are connected to form a left junction along the left side of said cell and said lower concave right end portion and said upper convex right end portion are connected to form a right junction along the right side of said cell, said honeycomb structure having a non-coated honeycomb density;
• and
• B) covering said honeycomb walls with a high temperature coating resin to form said flexible composite honeycomb, said coating resin being present in a resin coating amount that is equal to from 10 to 25 weight percent of the total weight of said composite honeycomb, said composite honeycomb having a density of from 3 to 6 pounds per cubic foot (48 to 96 kilograms per cubic meter) wherein the ratios between the first and second fibrous support weights and said resin coating amount is from 15:1 to 5:1 and wherein the width shear strength is at least 60 percent of said length shear strength.