Preparation And Performance Research Of Organic-inorganic Hybrid Fire-retardant Coating For Aircraft Composite Cabin

The wide application of composite decks in civil aircrafts has caused more and more attention to the issue of fire retardant in aircraft cabins.Traditional cabin fire-retardant coating have excellent p Hysical and chemical properties.Although they can meet the fire and airworthiness requirements of CCAR 23 and CCAR 25 of the Chinese Civil Aviation Regulations,they are difficult to meet the increasing environmental protection requirements due to the large amount of organic solvents used in their preparation.Organic-inorganic hybrid fire-retardant coating has the advantages of inorganic coatings such as high temperature resistance,abrasion resistance and high hardness.It also has the characteristics of organic coatings such as chemical resistance,corrosion resistance and high toughness.After film formation,it not only has excellent coating performance,but also has the unique characteristics of water-based coatings.Excellent characteristics such as environmental protection and low toxicity.However,the application of organic-inorganic hybrid fire-retardant coating on composite decks still has the disadvantages of high curing temperature,poor flexibility,and low adhesion,and there are few reports on its application in composite materials.In this thesis,the organic-inorganic hybrid fire-retardant coating are modified for their shortcomings,and the coating properties after film formation are studied,and their fire retardant properties are verified.The research content of the thesis is mainly divided into the preparation of basic coatings,the modification of coatings and the research of basic p Hysical and chemical properties,and the verification of fire retardant performance.First,the organic-inorganic hybrid base coating is prepared by the sol-gel method,and the coating is modified on this basis to reduce the curing time of the coating and increase the flexibility and adhesion of the coating.The single factor test method was used to compare aluminum acetylacetonate(AIAA),tetramethylammonium hydroxide pentahydrate(TMAH),guanidine hydrochloride(GCL),1,8-diazabicyclo[5.4.0]eleven carbon-7-ene(DBU),tetraethylammonium hydroxide(TEAH)five different types of catalysts and different additions have an impact on the performance of the coating.It is determined that the best catalyst is TMAH,and the surface drying time can be shortened to 30 min when the addition amount is 0.5 wt%.The thesis studied the different additives by adding three kinds of flexible nanoparticles:anionic polysiloxane emulsion(LZS-100 type),cationic polysiloxane emulsion(2051 type),and cationic polyacrylic emulsion(JH-1840 type).The impact of the amount on the performance of the coating.Studies have shown that the overall performance of the coating is the best when the addition amount of 2051 flexible nanoparticles is 1 wt%,and the flexibility of the coating can pass the 1 mm bending test at this time.The thesis studied the effect of different pigment additions on the coating performance through single factor experiments,and determined the optimal pigment addition to be 7 wt%.The thesis uses the orthogonal test method to optimize the coating formulation and determines that the coating exhibits the best performance when the catalyst,flexible nanoparticles,and pigments account for 0.5 wt%,5wt%,and 9 wt%of the total coating volume,respectively.In addition,in order to further improve the adhesion of the organic-inorganic hybrid coating to the composite deck,the thesis compares the laser surface treatment,manual polishing,and the micro-morp Hology and roughness of the original sample surface through the surface pretreatment of the composite deck.The influence of different surface treatment methods on the adhesion of the coating was studied.The results show that compared with the original sample,the adhesion of the coating after laser surface treatment is improved by2 levels,and compared with the manual grinding sample,the adhesion is improved by 1level.In order to verify the comprehensive performance of the modified coating,the thesis tested the p Hysical properties,chemical resistance and antibacterial properties of the coating.The study showed that the p Hysical properties of the modified coating include hardness,adhesion,flexibility,wear resistance and drop resistance.The hammer impact reached 7 H(pencil hardness),level 1(100 grid method),1 mm(bend),62.02%(500 g),and 50 cm(drop hammer impact),all of which were better than the base coating.The chemical resistance includes acid(CH₃COOH),alkali(Na CO₃),and salt(Na Cl)tests.The chemical resistance of the modified coating can reach 72 hours,meeting the application standards.The antibacterial properties of the modified coatings include testing of Escherichia coli and Stap Hylococcus aureus,reaching 24.2%and 24.6%respectively.The antibacterial properties need to be further improved.The thesis uses 60 s vertical combustion test,smoke density test and gas toxicity test to verify the airworthiness of the modified coatings for fire,smoke and poison.The result of the 60 s vertical burning test is a flame burning time of 8 s(<15 s),a scorch length of 94mm(?152 mm),and no drips.The smoke density of the coating is tested,and the result is199,which meets the airworthiness requirement?200.The test result is close to the airworthiness requirement limit and needs further improvement.The CO,CO₂,HF,NO_x,HCl,HCN,SO₂ gas concentrations released when the material is burned were tested,and the results were 375 ppm(?3500 ppm),14 ppm(?150 ppm),87 ppm(?200 ppm)),5 ppm(?500 ppm),1 ppm(?100 ppm),26 ppm(?100 ppm),all meet the airworthiness requirements.The results show that the organic-inorganic hybrid fire-retardant coating has excellent fire retardant performance.The thesis prepared a water-based organic-inorganic hybrid fire-retardant coating with normal temperature curing,high flexibility and strong adhesion through the orthogonal test method.Its fire retardant performance can meet the airworthiness requirements of CCAR 23and CCAR 25 regulations.The research results of the thesis provide important theoretical basis and technical support for its application in aircraft composite decks.