A kind of carbon/carbon composite material oxidation-proof coating
Technical field
The present invention is a kind of carbon/carbon composite material oxidation-proof coating, belongs to the high-temperature oxidation resistant coating technical field.
Background technology
Carbon/carbon composite is an advanced composite material that class density is low, mechanical behavior under high temperature is excellent, fracture toughness property is good, is used widely in the Aeronautics and Astronautics field.But carbon/carbon composite has a major defect, and promptly high-temperature oxidation resistance is poor, and the oxidation rate ratio is very fast more than 450 ℃, and along with temperature raises, oxidation is more and more serious.
Present most carbon/carbon composite is used for the aircraft brake disk material, and the temperature of brake flange may very high (above 900 ℃) during aircraft brake, must take effective anti-oxidation measure at the non-friction position of aircraft carbon/carbon composite brake flange.
Phosphoric acid salt is that main inoxidzable coating and relevant improved prescription is widely used at present, is characterized in that construction is simple, can be applied to long-term effectively below 800 ℃, but temperature when higher oxidation rate very fast, can not effectively protect.Phosphate coating in very fast inefficacy more than 850 ℃, loses oxidation-protective effect usually.
What another kind of research was more is the SiC coating, adopts pickling process sometimes, adopts the chemical vapor deposition (CVD) method sometimes.At high temperature, because SiC and O
2Reaction forms fine and close SiO
2Film, thereby good protection effect is arranged.But this type high temp coating thereby is not suitable for prolonged application in low temperature environment because the difference of the coefficient of expansion and the carbon/carbon composite coefficient of expansion causes cracking under the low temperature.
When using phosphoric acid salt for main compound inoxidzable coating, resin is an important component wherein, and thinner is toxic usually, in construction process sometimes with the smell of intense stimulus, operating environment needs ventilation effect preferably, but also can damage environment and personnel's health.
Summary of the invention
Purpose of the present invention designs at the shortcoming that exists in the prior art just and has proposed a kind of carbon/carbon composite material oxidation-proof coating, its objective is provide a kind of suitable carbon/carbon composite, can be at the inoxidzable coating of long term operation below 1000 ℃, make simultaneously that its making processes is nontoxic, non-volatility gas produces.
The objective of the invention is to realize by following measure:
This kind carbon/carbon composite material oxidation-proof coating is to be made of bottom and skin, it is characterized in that:
One, primer coating proportion of raw materials and making method are:
(1) with 0.5~2 Al (OH) that restrains
3With 5~15 gram Zn
3(PO
4)
24H
2O dissolves in H respectively
3PO
4In the solution, mix obtaining 20~25 milliliters clear solution then, add 5~40 milliliters water again;
(2) with the above-mentioned solution brushing for preparing on the carbon/carbon composite surface, under nitrogen atmosphere or vacuum protection, heat, be warming up to 500~900 ℃;
Two, outer coating proportion of raw materials and making method are:
(3) with 10~15 Na that restrain
2B
4O
710H
2O is dissolved in 10~50 milliliters the glycerol, adds the SiO of 10~50 grams then respectively
2The B powder of powder and 1~10 gram dilutes with 5~50 milliliters water again;
(4) with the above-mentioned coating brushing for preparing on the primer coating of carbon/carbon composite surface, again through 200 ℃ of oven dry 1 hour.
The bottom of the inoxidzable coating in the technical solution of the present invention also is a phosphate coating, but different with common phosphate coating, and the content of zinc phosphate is very high in this coating, and the content of aluminium hydroxide is lower.Show that by the oxidation test result under 700 ℃ of high temperature atmosphere the resistance of oxidation of the phosphate coating of technical solution of the present invention is compared with the usually phosphate coating, resistance of oxidation improves 20~50%.Thereby the phosphate coating that technical solution of the present invention provided also can use separately.
For outer coating, glycerol has certain viscosity can guarantee the bonding of coating and workpiece under the room temperature, dissolves Sodium Tetraborate simultaneously, and Sodium Tetraborate and silicon-dioxide form the good glass state material of protective when being convenient to thermal treatment.Glycerol is nonpoisonous and tasteless, can ensure construction environment preferably.But glycerol has water absorbability, should dry in baking oven behind the brushing outer coating.
Embodiment
Adopt technical solution of the present invention to carry out anti-oxidation processing at the non-friction position of aircraft carbon/carbon composite brake flange.
Its inoxidzable coating is to be made of bottom and skin, and its course of processing is as follows:
One, primer coating proportion of raw materials and making method are:
(1) primer coating proportion of raw materials and consumption are: H
3PO
4: 20 milliliters, Al (OH)
3: 0.5 gram, Zn
3(PO
4)
24H
2O:10 gram, H
2The O:20 milliliter;
Press said ratio with Al (OH)
3And Zn
3(PO
4)
24H
2O dissolves in H respectively
3PO
4In the solution, mix obtaining clear solution then, add 5~40 milliliters water again;
(2) with the above-mentioned solution brushing for preparing on the carbon/carbon composite surface, under nitrogen atmosphere or vacuum protection, heat, be warming up to 900 ℃;
Two, outer coating proportion of raw materials and making method are:
(3) outer coating proportion of raw materials and consumption are: Na
2B
4O
710H
2O:10 gram, SiO
2: 10 grams, B:2 gram, glycerol: 20 milliliters, H
2The O:20 milliliter;
Press said ratio with Na
2B
4O
710H
2O is dissolved in the glycerol, adds SiO then respectively
2Powder and B powder, water dilutes again;
(4) with the above-mentioned coating brushing for preparing on the primer coating of carbon/carbon composite surface, again through 200 ℃ of oven dry 1 hour.
The compound coating oxidation protection product that adopts technique scheme to make heats after 50 hours in 700 ℃ of air, and oxidation weight loss is less than 1%; Heating is 3 hours in 900 ℃ of air, and oxidation weight loss is also less than 1%.