Plasma is an electrically neutral, high-energy gaseous substance that is fully or partially ionized. It contains active particles such as ions, electrons, and free radicals, and is generated under conditions including high-frequency electromagnetic oscillation, radio frequency, microwave, high-energy rays, corona discharge, laser, and high temperature.

Plasma cleaning is a dry cleaning technology that removes contaminants from solid surfaces through reactions between active particles and pollutant molecules. It can replace traditional wet cleaning methods, effectively removing micro-dust and other contaminants from material surfaces without damaging surface properties.

Applicability of Plasma Cleaning Technology to Aviation Products

With the development of the aviation industry, awareness of precision manufacturing has increased. It is necessary to develop advanced cleaning technologies to replace conventional solvent-based cleaning, further improve cleaning performance, extend service life, enhance appearance quality, and reduce or eliminate harm to the human body caused by solvent volatilization.

Based on its working principle, plasma cleaning can be widely applied to pretreatment before coating, surface cleaning of bonded components, composite material manufacturing, and other fields in aviation products.

Treatment of Aluminum Alloy Skin Access Covers

In aviation manufacturing, aircraft skin access covers are made of aluminum alloy. To improve sealing performance, nitrile rubber is vulcanized to form gaskets at the pressing areas. However, excess rubber often overflows after vulcanization and contaminates surfaces to be coated, reducing coating adhesion and leading to easy peeling.

Conventional cleaning cannot completely remove such contamination, affecting the performance of access covers. With plasma cleaning prior to coating, coating adhesion is significantly improved and meets aviation coating standards.

Aerospace Electrical Connectors

Requirements for electrical connectors in aerospace are extremely stringent. Untreated insulators exhibit poor adhesion with sealing components, even when special adhesives are used. In addition, poor bonding between insulators and sealing parts may cause leakage and low withstand voltage, severely restricting the development of domestic electrical connectors.

Leading domestic manufacturers of aerospace electrical connectors are gradually adopting plasma cleaning. Plasma treatment not only removes surface oil contamination but also enhances surface activity, making adhesive application easier and more uniform, with significantly improved bonding strength.

Tests by major manufacturers show that plasma-cleaned connectors have several times higher tensile strength and greatly improved voltage withstand performance.

Composite Material Manufacturing

High-performance continuous fibers (carbon fiber, aramid fiber, PBO fiber, etc.) reinforced thermoset and thermoplastic resin matrix composites are widely used in aviation, aerospace, and military fields due to their light weight, high strength, and stable performance.

However, these fibers usually have smooth surfaces and low chemical activity, making it difficult to achieve physical interlocking and chemical bonding between fibers and resin matrices, resulting in weak interfacial bonding and reduced overall performance.

Moreover, commercial fibers are often covered with organic sizings and micro-pollutants from production, sizing, transportation, and storage, which further weaken interfacial adhesion.

Therefore, before composite fabrication, fibers require plasma treatment for cleaning and etching. This process removes organic coatings and contaminants, introduces polar or active groups, and creates reactive sites that can initiate grafting and crosslinking.

Through the combined effects of cleaning, etching, activation, grafting, and crosslinking, the physical and chemical state of fiber surfaces is improved, thereby strengthening the interaction between fibers and the resin matrix.

Other Applications in Aviation Manufacturing

Plasma cleaning also has broad applications in aviation manufacturing, such as:

1. Treatment of door and window seals to improve sealing performance;

2. Pretreatment of instrument panels before coating to prevent paint peeling;

3. Surface activation of control panels before bonding to increase adhesion strength;

4. Precision parts cleaning to remove oil residues left by machining.