Information about components for supersonic aircraft
In the realm of aerospace engineering, Dr. Susan Krumdieck from the University of Canterbury is making strides in developing oxygen-resistant ceramic coatings for hypersonic vehicles. These coatings are crucial as hypersonic vehicles, which travel at speeds exceeding Mach 5, experience extreme temperatures and oxidative environments during flight.
The challenge lies in the high thermal loads generated by these vehicles, leading to oxidation and degradation of materials. Conventional coatings often fail to provide sufficient protection, especially under oxygen-rich, high-temperature conditions.
To address this issue, Dr. Krumdieck focuses on ceramic materials, known for their excellent thermal resistance and chemical stability. However, many ceramics can still be vulnerable to oxygen attack at hypersonic temperatures. To overcome this, she employs a technique called Plasma-Enhanced Physical Chemical Vapor Deposition (PPCVD).
PPCVD allows the formation of high-quality thin ceramic films. In this method, a precursor gas containing the ceramic-forming elements is introduced into a vacuum chamber. A plasma is generated to enhance chemical reactions at lower temperatures than traditional CVD, allowing better control over film properties. The ceramic coating grows atom-by-atom on the substrate, resulting in dense, uniform, and adherent layers.
This process offers several advantages in coating development. PPCVD enables precise control over the microstructure and composition of the ceramic films. It can tailor coatings to be more resistant to oxidation by optimizing phases and grain boundaries. Furthermore, it can deposit multilayer or composite coatings to further enhance protection.
Dr. Krumdieck's research aims to develop coatings that maintain structural integrity and oxidation resistance during the extreme service conditions of hypersonic flight, thereby improving vehicle longevity and safety.
In collaboration with the US National Hypersonic Science Centre (NHSC), Dr. Krumdieck is working on new materials for hypersonic vehicles. Analysis methods include scanning electron microscopy (SEM) and X-ray diffraction (XRD). Samples made on NASA's SiC composite material will be sent to the University of California at Santa Barbara for high-temperature testing and to Berkeley for micro-cat-scan analysis.
Dr. Krumdieck refers to her research as 'What if?' science, solving challenges for things that don't exist yet, such as hypersonic vehicles. The hypersonic vehicle will be made of woven silicon carbide (SiC) ceramic composites, and an oxygen-resistant ceramic coating is required due to the intensely hot conditions of hypersonic flight.
The process involves a liquid chemical precursor containing metal oxides bound to hydrocarbon molecules, which is turned into a vapor and used to grow ceramic layers on objects. The temperature at which the ceramic crystals grow can be changed as a variable, and the amount of precursor injected at each pulse is controllable. The rate at which the precursor liquid is injected can also be adjusted. Adding in other materials, such as alumina, can be considered.
A coating of less than a millimeter of ceramic can protect a structure from erosion and chemical attack. By using the PPCVD process, Dr. Susan Krumdieck is engineering advanced ceramic coatings that can withstand harsh oxidative environments encountered by hypersonic vehicles, leveraging plasma-enhanced deposition to produce coatings with enhanced performance characteristics.
- In her research, Dr. Susan Krumdieck combines the fields of science and technology, specifically focusing on the development of advanced ceramic coatings for hypersonic vehicles.
- As scientific advancements in technology continue, such as Dr. Krumdieck's ceramic coatings, the practical applications extend beyond existing systems, like hypersonic vehicles, and may one day lead to the creation of new ones.
