There are two commonly used insulating materials for aerospace wires and cables, one is polytetrafluoroethylene, and the other is polyimide and polytetrafluoroethylene composite.


The thickness and uniformity of the insulation layer, as well as the overlapping accuracy of multi-layer insulation layers, are all basic testing items for quality process control.


At the invitation of metallographic engineers from some aerospace wire and cable manufacturers, metalworking from Chain Energy Metallographic Experimental Equipment Nanjing Co., Ltd. provided free practical guidance on sample preparation and microscopic observation.


1、 Insulation material sample


Sample A, X-ETFE (cross-linked F40), cross-linked ethylene tetrafluoroethylene copolymer material, with conductor. Only measure the thickness of the insulation layer, and the standard requires an accuracy of 0.01mm.


Sample B, PTEF/PI, polyimide and polytetrafluoroethylene composite film, without conductor, only with insulation layer. Detect the spacing between insulation layers with an accuracy of 0.01mm, and simultaneously detect the overlap angle between the inner and outer insulation layers with an accuracy of 0.1 degrees.


2、 Embedding of two types of insulation materials


Take four Φ 30mm SamplCup reusable injection cup.


Clamp the sample with a UniClip tripod plastic clip and place it in the injection cup.


Using EpoQuick epoxy resin and curing agent cured by QMAXIS (Pulse Detection) in the United States for two hours, pour them into a mixing wax paper cup in a 5:1 ratio, slowly stir in the same direction with a stirring rod for about 2 minutes, and pour them into the injection molding cup separately.


Fully cure in about two hours.


3、 Grinding and polishing of two types of insulation materials


Adopting an automatic polishing scheme, the polishing machine is METPOL-A automatic polishing machine.


The preparation plan is as follows:

4、 Microscopic observation of two types of insulation materials


Sample A, insulation layer thickness approximately 110 μ m. Tolerance≤ two point one μ M

Sample B, insulation layer spacing approximately 17 μ m. Tolerance≤ one point six five μ M

Sample B, insulation layer overlap angle approximately 89.2 degrees

5、 Conclusion


Two types of insulation layer thickness tolerances tested≤ two point one μ m. Meet the standards of technical conditions. For sample B, polyimide and polytetrafluoroethylene composite film, the overlapping angle tolerance of insulation layer is 0.8 degrees, which meets the standard of technical conditions.


The metallographic engineers who participated in the observation not only learned the technical details of inlaying and polishing from the chain energy metallographic workers, but also felt the importance of their own testing and analysis work& Flash; Being able to promptly identify problems in production, provide accurate testing data to production and R&D departments, adjust processes, and produce qualified products. It can also provide technical support for sales departments to participate in technical exchanges and bidding for aerospace wires and cables.