The adhesion performance of high-temperature tape in high-temperature environments is closely related to its surface roughness. This correlation is not only reflected in the strength of adhesion but also in the stability, durability, and functional integrity of the tape-adhesive interface at high temperatures. Surface roughness, as a key parameter, directly determines the overall performance of high-temperature tape under extreme conditions by influencing wetting behavior, mechanical locking, and thermal stress distribution.
When high-temperature tape is applied to a smooth surface, the contact area between the adhesive and the substrate is limited, making it difficult to form sufficient intermolecular forces. In this case, if the surface roughness is moderate, the micro-uneven structure can significantly increase the actual contact area, allowing the adhesive to fully penetrate into the micropores of the substrate surface, forming a mechanical locking effect. This effect is particularly important in high-temperature environments—when the adhesive softens due to heat, the mechanical locking structure can effectively resist shear and peel forces, preventing the tape from detaching due to tack decay. For example, in the thermal insulation of hot-end components of aero-engines, high-temperature tape needs to withstand the scouring of high-temperature airflow for extended periods. Appropriate surface roughness ensures a strong bond between the tape and the substrate, preventing detachment due to vibration or thermal expansion.
However, higher surface roughness is not always better. When roughness exceeds a critical value, sharp protrusions on the surface of the adherend may puncture the adhesive layer, creating localized stress concentration points. At high temperatures, the adhesive softens due to heat, reducing its elastic modulus. These stress concentration points are prone to crack propagation, leading to premature failure of the tape-adhesive interface. Furthermore, excessive roughness may hinder the uniform spread of the adhesive, creating weak areas and further reducing bond strength. For instance, in electronic component packaging, if the substrate surface roughness is too high, the high-temperature tape may warp or delaminate during curing due to uneven localized stress, affecting sealing performance.
The impact of high-temperature environments on surface roughness is also reflected in thermal expansion compatibility. Differences in the coefficients of thermal expansion of different materials can lead to a redistribution of interfacial stress at high temperatures. If the surface roughness of the adhered materials is high, thermal deformation of their microstructure may induce non-uniform strain in the adhesive layer, accelerating interfacial debonding. For example, in the bonding of metal and ceramics, while the rough structure formed by sandblasting the metal surface can enhance initial adhesion, under high-temperature cyclic loading, the difference in the thermal expansion coefficients of the metal and ceramics may cause microcracks at the roughness peaks, ultimately leading to macroscopic debonding.
Surface roughness also indirectly affects high-temperature bonding performance by influencing the rheological behavior of the adhesive. At high temperatures, the viscosity of the adhesive decreases, and its flowability increases. Appropriate surface roughness can guide the adhesive's directional flow, filling micro-gaps and forming a dense adhesive layer; however, if the roughness is too high, the adhesive may accumulate at the troughs due to excessive flow, resulting in insufficient coverage at the peaks and forming defects. These defects are prone to becoming the starting point for oxidation or corrosion at high temperatures, reducing the long-term stability of the tape.
From a practical application perspective, the surface roughness of high-temperature tape needs to be optimized based on the material of the adhered materials, the operating temperature, and the type of load. For example, in high-temperature sealing scenarios, the surfaces of the adhered objects typically require sanding or chemical etching to create a uniform micro-rough structure; while in high-temperature insulation scenarios, roughness must be controlled to avoid partial discharge caused by electric field concentration. Furthermore, the substrate and adhesive system of high-temperature tape must also match the surface roughness—rigid substrates can withstand the stress from higher roughness, while flexible substrates require lower roughness to prevent localized deformation.
The impact of high-temperature tape surface roughness on high-temperature bonding performance is the result of multiple mechanisms. Appropriate roughness can enhance mechanical locking, improve wettability, and optimize thermal stress distribution, thereby improving bond strength and durability; however, excessively high or low roughness can lead to interface defects, stress concentration, or rheological runaway, ultimately causing bonding failure. Therefore, in the design and application of high-temperature tape, surface roughness must be precisely controlled through experiments and simulations to achieve optimal overall performance.
