Annotation: Gasars is a new type of porous cast materials manufactured on the basis of metals and their alloys, some types of ceramics. The basis of the process is gas-eutectic conversion in the system metal-hydrogen. The process of investigation and creation of gasars was commenced in 1979 in the National Metallurgical Academy of Ukraine and is currently continued in Ukraine, the USA, China, Japan, South Korea, Poland and others. The gasars production technological process consists in melting the specified material (metal, alloy, ceramics) in hydrogen (or other active gas) atmosphere at a certain pressure. After the melt is saturated with active gas to a certain concentration, the crystallization process begins at which the pore formation process is launched. As the pores growth occurs perpendicular to crystallization front, the orientation of heat withdrawal influences pores location. So, for example, to obtain radial porosity, radial heat withdrawal is required. To obtain various structures, along with directed crystallization process, the pressure in crystallization chamber is an important factor, which drives the gasar morphology. The porous structure of gasars is diverse, there are the gasars with longitudinal, cylindrical, spherical, conical pores. It is possible to alternate the porosity layers and monolithic metal layers. The dimensions of gasars pores are in the limits from 10 μm to 10 mm at total porosity from 7 to 55 (75%). However, there is a possibility to obtain the pores with smaller diameter. The mechanical properties of gasars have a number of advantages as compared with conventional porous materials produced by different methods. Subsequent processing of the gasars does not differ from analogous non-porous materials, which is also an advantage over conventional porous materials. And in case when the diameter of pores is less than 50 μm, the exceedance of mechanical properties of gasars as compared with monolithic materials of the same chemical composition is observed. This is caused by the fact that the pores were formed during crystallization and at the action of pressure on a gasar, local hardening occurs. At present, the gasars have already found application as light and strong structural materials, filters, heat exchangers, dampers, slide bearings, catalyst elements, friction materials, etc. The use of gasars in space hardware will help to considerably reduce the mass of launch vehicle structural elements without worsening strength properties. The possibility of welding and soldering the gasars allows finding their application in the structure of propellant systems, compressed gas and propellants supply systems, creating filtering elements based on the gasars, including propellant spraying and mixing systems.

Annotation: Explosive bolts are widely used as actuating devices in the spacecraft separation systems. Explosive bolt body is divided into parts as a result of engagement of the pyromixture placed inside. Activated explosive bolts have negative mechanical effect on the interface elements and sensitive electronic devices installed nearby owing to explosive behavior of the pyromixture combustion, generating shock front with high pressure and velocities, impacts and collisions of the structural units. Cumulative effect of the above factors on the separated objects is called pyroshock. For separation systems with increased requirements to external actions and cleanliness, authors developed a shear explosive bolt or pyrobolt, divided into parts, cutting the body walls in segments, which are set in motion by action of the pressure of gases, released as a result of pyrocartridge activation. The basic sources of pyroshock for these shear explosive bolts with segments are: combustion of pyromixture, internal impacts of structural units against the bolt body; cutting of body wall in segments, release of preliminary deformed interface after activation. Structural solutions are presented to reduce the pyroshock per each of the components. Vibration impulsive loading during pyromixture combustion is reduced by optimization of explosive quantity, finding its minimum to provide the reliable activation of the device. To reduce the impact on the explosive bolt elements and shock front interface the rubber gasket is installed in the path of shock wave distribution, partially disseminating and absorbing its kinetic energy. Damper, made of easily deformable aluminum alloy, is also installed to decrease the internal impact of the rod against the explosive bolt body. Functional testing of the device, using the pendulum suspension and measuring separation speed and vibration impulsive loading, showed that body parts of the shear explosive bolt with segments are separated without significant impact loads and discharge of high-temperature gases and debris, providing reliable separation of compartments and units without damaging the sensitive equipment. Obtained values of the mechanical momentum, I = 0,4÷0,7 N•s and shock load spectrum – g-load 1950 g at the frequency range up to 5000 Hz, meet the up-to-date requirements to pyrotechnical devices.