FIELD: biotechnology.
SUBSTANCE: method of qualitative assessment of biocorrosion damages of thin-walled sealed enclosures of aluminium-magnesium alloys in operation of spacecrafts and the suspension of spore materials fungi of implementation of the said method is proposed. The test and control samples of aluminium and magnesium alloys are prepared. The prepared samples are dried, sterilised. Fungal cultures - strains of microorganisms Paecilomyces variotii Bainier of All-Russian collection of microorganisms F-4039D, Ulocladium botrytis Preuss of All-Russian collection of microorganisms F-4032D, Penicillium chrysogenum Thorn of All-Russian collection of microorganisms F-4034D, Aspergillus sydowii (Bainier et Sartory) Thorn et Church of All-Russian collection of microorganisms F-4037D, Cladosporium sphaerospermum Penz. of All-Russian collection of microorganisms F-4041D are inoculated for growing spores into tubes with a sloped agar medium of Czapek-Dox. The tubes are thermostated at a temperature of (29+2)°C for 14-28 days until appearance of mature spores. Spore materials suspensions of individual cultures of the said fungi are prepared, which are then mixed in equal proportions. And the concentration of spores of each fungi species in the suspension should be in the range of 1-2 mln/cm3. The resulting suspension is applied to the sterilised test samples. Then they are dried and placed as one sample in each Petri dish on the surface of agar medium of Czapek-Dox. The control samples not treated by the spore material are also placed on the surface of the agar medium of Czapek-Dox in the Petri dishes. The Petri dishes with the test and control samples are placed in different desiccators at the bottom of which water is poured to maintain the humidity more than 90%. The desiccators are closed and incubated in the thermostat at a temperature of (29±2)°C. The exposition of test and control samples is carried out for 40, 120 and 180 days. Then the samples are removed from the Petri dishes, and the corrosion products and mycelium are removed from the surface of the samples washing them in running water. The samples are soaked in 70% ethyl alcohol for 30 minutes, then they are washed with detergent and dried. Then, using a scanning electron microscope a qualitative assessment of biocorrosion damages is carried out. According to the change in the appearance of the surface of the samples the initial stages of biocorrosion and its type is evaluated, as well as the distribution of corrosion damage on the surface of the samples, and the dependence of the biocorrosion process on time is determined.
EFFECT: inventions enable to carry out the qualitative assessment of the initial stages of biocorrosion damages of thin-walled sealed enclosures of aluminium-magnesium alloys with the thickness of more than 2 mm.
2 cl, 9 tbl
