METHOD FOR REPAIRING DAMAGE ON NON-FRICTION SURFACE OF CARBON BRAKE DISC OF AIRCRAFT

Abstract

A method for repairing damage on a non-friction surface of a carbon brake disc of an aircraft, includes: removal of a damaged region, cutting of a repair material, anti-oxidation modification of the repair material, bonding and curing, and high-temperature heat treatment. The anti-oxidation modification is performed on the repair material without affecting the mechanical properties of the repair material, which improves the anti-oxidation ability of the repair zone and avoids the preparation of an anti-oxidation coating. In this way, only the damage on the non-friction surface is repaired, and there is little effect on the mechanical properties, friction and wear properties and thermal conductivity of the carbon-carbon composite material.

Claims

1. A method for repairing a damage on a non-friction surface of a carbon brake disc of an aircraft, comprising the following steps: step 1): removal of a damaged region: visually inspecting the damage on the non-friction surface of the carbon brake disc, determining a damage removal area, and marking the damage removal area, wherein the damage removal area is wider than an edge of the damaged region, the damage removal area is round or elliptical, and a maximum removal depth is a maximum depth of the damage; after the damage removal area is marked, polishing the damage removal area into a slope shape by using a polishing tool to obtain a polished damaged carbon brake disc; machining first glue-flowing grooves on a polished surface; placing the polished damaged carbon brake disc in an ultrasonic cleaner for cleaning, and then transferring the polished damaged carbon brake disc into a vacuum drying oven for drying; step 2): cutting of a repair material: obtaining the repair material with a volume larger than the damage removal area of the carbon brake disc to be repaired by cutting a scrap carbon brake disc through mechanical processing; polishing the repair material until the repair material is equivalent to the damage removal area; machining second glue-flowing grooves on a bonding surface of the repair material; placing the repair material after being polished in the ultrasonic cleaner for cleaning, and then transferring the repair material into the vacuum drying oven for drying; step 3): anti-oxidation modification of the repair material: step 3.1): mixing and stirring evenly Al.sub.2O.sub.3, B.sub.2O.sub.3, TiO.sub.2 and ZrB.sub.2 powders to obtain mixed powders; step 3.2): adding lithium tetraborate to a sodium silicate aqueous solution to obtain a first solution, and stirring the first solution to obtain a stable solution; then adding the mixed powders obtained in step 3.1) into the stable solution to obtain a second solution, and stirring well the second solution to obtain a modifying solution; step 3.3): pouring the modifying solution obtained in step 3.2) into an impregnating tank, completely impregnating the repair material in the modifying solution, and then vacuumizing the impregnating tank for vacuum impregnation to obtain an impregnated repair material; and step 3.4): drying the impregnated repair material, and then curing the impregnated repair material in an oven at 80-120° C. for 2-4 h; step 4): bonding and curing: applying an adhesive to the non-friction surface of the carbon brake disc to be repaired and the bonding surface of the repair material, and bonding the repair material to the damage removal area; clamping the carbon brake disc to be repaired and the repair material by using a clamp, and removing a spilled excess of the adhesive; putting the carbon brake disc with the repair material into the oven for curing; then removing a vacuum bag after curing, and polishing and smoothing a repair zone to obtain a smoothed carbon brake disc; and step 5): heat treatment: placing the smoothed carbon brake disc obtained in step 4) into a pre-vacuumized pyrolysis furnace protected by being filled with N.sub.2 for heating and a first heat preservation, and then cooling the smoothed carbon brake disc to room temperature within the pre-vacuumized pyrolysis furnace to obtain a repaired carbon brake disc.

2. The method according to claim 1, wherein in step 1), a slope of the slope shape is 1:15 to 1:20.

3. The method according to claim 1, wherein in step 3.1), before mixing, the Al.sub.2O.sub.3, B.sub.2O.sub.3, TiO.sub.2 and ZrB.sub.2 powders are respectively milled in a ball mill for 12 h, then sieved through a 325-mesh sieve, and dried in the oven at 120° C. for 6 h.

4. The method according to claim 1, wherein in step 3.1), the Al.sub.2O.sub.3, B.sub.2O.sub.3, TiO.sub.2 and ZrB.sub.2 powders have a weight ratio of 1:1.2:0.8:0.5.

5. The method according to claim 1, wherein in step 3.2), a mass of the lithium tetraborate is 1-6% of a mass of the sodium silicate aqueous solution, and a mass of the mixed powders are 10% of the mass of the sodium silicate aqueous solution; the sodium silicate aqueous solution has a modulus of 2.8-3.2.

6. The method according to claim 1, wherein in step 3.3), the vacuum impregnation is carried out under 40-60 kPa for 1-4 h.

7. The method according to claim 1, wherein in step 4), the adhesive is prepared as follows: mixing a resin in an organic solvent to obtain a third solution; then adding an inorganic filler, a catalyst and a curing agent into the third solution to obtain a fourth solution; and stirring the fourth solution to obtain the adhesive.

8. The method according to claim 7, wherein the resin is at least one selected from the group consisting of an organic silicone resin and an epoxy resin; the inorganic filler is at least one selected from the group consisting of aluminum, boron carbide and glass powder.

9. The method according to claim 1, wherein in step 4), the curing is carried out by heating to 120-160° C. at 5° C./min and performing a second heat preservation for 3 h.

10. The method according to claim 1, wherein in step 5), the heat treatment in the pre-vacuumized pyrolysis furnace is carried out by heating to 700° C. and performing the first heat preservation for 2 h.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] In order to make the present invention more understandable, preferred embodiments are described in detail as follows.

Embodiment 1

[0029] A method for repairing a damage on a non-friction surface of a carbon brake disc of an aircraft includes five steps, namely removal of a damaged region, cutting of a repair material, anti-oxidation modification of the repair material, bonding and curing, and high-temperature heat treatment. The specific process steps are as follows:

[0030] (1) Removal of the damaged region: visually inspecting the damage on the non-friction surface of the carbon brake disc, determining a damage removal area, and marking the damage removal area, where the damage removal area is wider than the edge of the damaged region, the removal area is round or elliptical, and the maximum removal depth is the maximum depth of the damage; after the damage removal area is marked, polishing the damage removal area into a slope shape with a slope of 1:15 to 1:20 by using a polishing tool; machining glue-flowing grooves on a polished surface; placing the polished damaged carbon brake disc in an ultrasonic cleaner for cleaning, and then transferring the polished damaged carbon brake disc into a vacuum drying oven for drying.

[0031] (2) Cutting of the repair material: obtaining the repair material with a volume larger than the damage removal area of the carbon brake disc to be repaired by cutting a scrap carbon brake disc through mechanical processing; polishing the repair material until the repair material is equivalent to the damage removal area; machining glue-flowing grooves on a bonding surface of the repair material; placing the repair material after being polished in the ultrasonic cleaner for cleaning, and then transferring the repair material into the vacuum drying oven for drying.

[0032] (3) Anti-oxidation modification of the repair material:

[0033] {circle around (1)} Powder treatment: respectively milling Al.sub.2O.sub.3, B.sub.2O.sub.3, TiO.sub.2 and ZrB.sub.2 powders in a ball mill for 12 h, then sieving through a 325-mesh sieve, and drying in an oven at 120° C. for 6 h to obtain processed powders; evenly stirring the processed powders in a ratio of 1:1.2:0.8:0.5 in a stirrer.

[0034] {circle around (2)} Solution preparation: adding 1 wt % lithium tetraborate to a sodium silicate aqueous solution, and stirring at 1000 rpm for 4 h to obtain a stable solution; then adding 10 wt % of the mixed powders prepared in step {circle around (1)}, and stirring well to obtain a modifying solution.

[0035] {circle around (3)} Impregnation: pouring the modifying solution obtained in step {circle around (2)} into an impregnating tank, completely impregnating the repair material in the modifying solution, then vacuumizing to 40 kPa, and impregnating for 4 h.

[0036] {circle around (4)} Curing: drying the impregnated repair material, and then curing in the oven at 80° C. for 4 h.

[0037] (4): Bonding and curing: applying a prepared adhesive to the carbon brake disc to be repaired and the bonding surface of the repair material, and bonding the repair material to the damage removal area; clamping by using a clamp, and removing a spilled excess of the adhesive; putting the carbon brake disc with the repair material into the oven for curing by heating to 250° C. at 5° C./min and performing heat preservation for 3 h; then removing the clamp after curing, and polishing and smoothing the repair zone.

[0038] (5) High-temperature heat treatment: placing the carbon brake disc to be repaired after being treated in step (4) into a pre-vacuumized pyrolysis furnace protected by being filled with N.sub.2, heating the carbon brake disc to 500° C. and performing heat preservation for 4 h, and then cooling to room temperature with the furnace to obtain a repaired carbon brake disc.

Embodiment 2

[0039] A method for repairing a damage on a non-friction surface of a carbon brake disc of an aircraft includes five steps, namely removal of a damaged region, cutting of a repair material, anti-oxidation modification of the repair material, bonding and curing, and high-temperature heat treatment. The specific process steps are as follows:

[0040] (1) Removal of the damaged region: visually inspecting the damage on the non-friction surface of the carbon brake disc, determining a damage removal area, and marking the damage removal area, where the damage removal area is wider than the edge of the damaged region, the removal area is round or elliptical, and the maximum removal depth is the maximum depth of the damage; after the damage removal area is marked, polishing the damage removal area into a slope shape with a slope of 1:15 to 1:20 by using a polishing tool; machining glue-flowing grooves on a polished surface; placing the polished damaged carbon brake disc in an ultrasonic cleaner for cleaning, and then transferring the polished damaged carbon brake disc into a vacuum drying oven for drying.

[0041] (2) Cutting of the repair material: obtaining the repair material with a volume larger than the damage removal area of the carbon brake disc to be repaired by cutting a scrap carbon brake disc through mechanical processing; polishing the repair material until the repair material is equivalent to the damage removal area; machining glue-flowing grooves on a bonding surface of the repair material; placing the repair material after being polished in the ultrasonic cleaner for cleaning, and then transferring the repair material into the vacuum drying oven for drying.

[0042] (3) Anti-oxidation modification of the repair material:

[0043] {circle around (1)} Powder treatment: respectively milling Al.sub.2O.sub.3, B.sub.2O.sub.3, TiO.sub.2 and ZrB.sub.2 powders in a ball mill for 12 h, then sieving through a 325-mesh sieve, and drying in an oven at 120° C. for 6 h to obtain processed powders; evenly stirring the processed powders in a ratio of 1:1.2:0.8:0.5 in a stirrer.

[0044] {circle around (2)} Solution preparation: adding 6 wt % lithium tetraborate to a sodium silicate aqueous solution, and stirring at 1000 rpm for 4 h to obtain a stable solution; then adding 10 wt % of the mixed powders prepared in step {circle around (1)}, and stirring well to obtain a modifying solution.

[0045] {circle around (3)} Impregnation: pouring the modifying solution obtained in step {circle around (2)} into an impregnating tank, completely impregnating the repair material in the modifying solution, then vacuumizing to 60 kPa, and impregnating for 1 h.

[0046] {circle around (4)} Curing: drying the impregnated repair material, and then curing in the oven at 120° C. for 2 h.

[0047] (4): Bonding and curing: applying a prepared adhesive to the carbon brake disc to be repaired and the bonding surface of the repair material, and bonding the repair material to the damage removal area; clamping by using a clamp, and removing a spilled excess of the adhesive; putting the carbon brake disc with the repair material into the oven for curing by heating to 250° C. at 5° C./min and performing heat preservation for 3 h; then removing the clamp after curing, and polishing and smoothing the repair zone.

[0048] (5) High-temperature heat treatment: placing the carbon brake disc to be repaired after being treated in step (4) into a pre-vacuumized pyrolysis furnace protected by being filled with N.sub.2, heating the carbon brake disc to 700° C. and performing heat preservation for 2 h, and then cooling to room temperature with the furnace to obtain a repaired carbon brake disc.