Experimental study on defects of needled quartz fiber reinforced phenolic aerogel composites by cryogenic milling

Needled quartz fiber reinforced phenolic aerogel composite (NQF/PA) is a kind of lightweight thermal protection material commonly used in the aerospace field. With the continuous development of aerospace science and technology, the design of various spacecraft is becoming more and more complex. Due to the limitation of the preparation process, thermal protection components are difficult to be directly prepared and formed. It is often necessary to carry out secondary processing in order to bond and assemble into a large-size combined thermal protection system. Because NQF/PA composites have the characteristics of high fiber toughness and easy cracking of the matrix, it is easy to cause processing defects such as burrs, tearing and edge collapse in dry machining. Cryogenic machining can improve the machinability of fiber-reinforced composites. However, there is still a lack of research on the cryogenic machining of NQF/PA composites. In order to analyze the feasibility of cryogenic machining technology for low-damage processing of NQF/PA composites, this paper carried out a comparative experimental study on dry machining and cryogenic machining of NQF/PA composites and analyzed the influence of spindle speed, feed rate and radial cutting depth on surface defects and cutting force. The research showed that under the same processing parameters, compared with dry machining, cryogenic machining can effectively reduce the cutting force and suppress processing defects.