I. Core Breakthroughs

Breakthrough 1 : Aviation in One Step RTM Titanium / Filling the gap in quantitative benchmarks for carbon-integrated joint manufacturing processes.

Traditional titanium - Composite joints are typically fabricated by forming first and then bonding with adhesive. /  The riveting process is carried out in multiple steps, and there is a lack of dedicated interface data for the co-injection one-step molding stage. This paper fully aligns with the standards of aircraft engines. OGV Real-part material system ( IMS65 Carbon ribbon + RTM6 Epoxy + 5 grade titanium alloy), establish 5  A comprehensive performance database for mainstream surface treatments has been established, filling the gap in quantitative testing of heterogeneous joints produced via one-step co‑molding and enabling direct application to aerospace structural process design.

Breakthrough 2 : Distinguish mechanical anchoring + Chemical activation–induced dual-interface enhancement mechanism: clarifying the boundaries between advantages and disadvantages.

Successfully demonstrated the complete differentiation of two types of surface-modification logics: laser / Sandblasting achieves mechanical interlocking through micro‑grooves, while plasma treatment relies on highly reactive functional groups for chemical activation. It is clear that chemical activation alone cannot establish a reliable shear‑bearing interface; resin anchorage must be complemented by a micro‑roughened surface morphology. This elucidates the fundamental mechanism underlying plasma‑induced bond failure in the absence of a primer and corrects the industry’s one‑sided belief that plasma activation alone can enhance adhesion.

Breakthrough 3 : Revealing the Differentiation Patterns Between Pull-Out Tests and Single-Lap Shear Performance

The industry often relies on simple pull‑out tests for rapid process screening; however, this study demonstrates that the results from these two methods do not exhibit a linear correlation: while plasma treatment yields a slight increase in pull‑out strength, shear testing reveals complete debonding; and although scouring pad roughness shows no significant improvement, its shear performance ranks second. These findings underscore that pull‑out tests should be used only as a quick preliminary screening tool, and that for aerospace load‑bearing joints, single‑lap shear strength must serve as the primary evaluation criterion, thereby refining the standardized testing framework for interface assessment.

Breakthrough 4 : Primer “ Reduce intensity in the short term, enhance durability over the long term. ”  Quantification of the Double-Edged Effect

Systematic quantification of the dual‑sided effects of epoxy primers: After all treatments and primer application, both instantaneous pull‑out and shear strengths decrease. 15%~32% However, the primer seals the polar active sites on the titanium surface, preventing interfacial corrosion and delamination under humid‑heat cycling conditions. It perfectly meets the design requirements of aerospace components for long service life and high environmental stability, providing… “ Short-term mechanics /  Long-term durability ”  Basis for process selection.

II. Technological Innovation

Innovation 1 5 Standardized Comparative Test System for Titanium‑Like Surface Treatments

Mechanical processing

• Scouring pad ( Silly person ): Hand-polished in both horizontal and vertical directions, resulting in a slight reduction in surface roughness;
• Aluminum oxide sandblasting ( South Africa ): Uniform micro-pits, with roughness increased by nearly 1  times;
• Laser micro-texturing ( L ): 200W Laser-fabricated regular microgrooves with a surface roughness reaching the original level. 100  More than double;

Chemistry / Activation-type processing

• Concentrated sulfuric acid etching ( E ): Mildly increases roughness and slightly enhances surface energy;
• Atmospheric-pressure plasma ( P ): No change in morphology; significant enhancement of polar functional groups; chemical activation only.
• Are all processes uniformly matched with or without? HexBond Two groups of epoxy primers were used as controls, with a single variable held constant, ensuring that the data are suitable for cross‑group comparisons.

Innovation 2 Multi-dimensional interface comprehensive characterization test chain

• Surface morphology: Three-dimensional scanning with an optical profiler provides a direct visualization of the surface’s micro‑grooves and pits.
• Physicochemical scale: Contact angle method ( Fowkes Model) Dispersion Splitting /  Polar surface free energy, which quantifies the degree of surface activation;
• Interface‑based rapid evaluation: pull‑off adhesion testing for quick preliminary screening of process quality;
• Engineering Mechanics Benchmark: EN 2243-6 Standard single-lap shear test, simulating the in-plane loading conditions of aerospace components;
• The entire characterization suite covers the micro‑morphology. — Surface Chemistry — Instant adhesion — The structure supports the entire value chain.

Innovation 3 AFP Prefabricated component + One step RTM Integrated Molding Process Support Solution

Adopt ABB Robot-mounted AddComposites AFP Preparation of dry carbon preforms by layer-by-layer deposition, laying-up speed 250mm/s ; Mold-embedded titanium plate +  Dry fiber synchronous positioning, 0.7 bar Low-pressure resin impregnation, maximum 6 bar Compaction eliminates porosity, enabling the one-step co‑curing of titanium inserts with composite materials, thereby eliminating secondary bonding and mechanical fastening steps and reducing assembly weight and labor time.

Innovation 4 Mechanistic Physical Explanation Model for Interface Strengthening

• Mechanical locking mechanism: laser / Sandblasting creates micron‑scale surface irregularities; after the resin cures, it fills these grooves, establishing physical anchorage and significantly enhancing shear resistance.
• Chemical bonding mechanism: Plasma treatment and etching generate hydroxyl groups and polar titanium‑oxide functional groups, enhancing resin wetting; however, in the absence of a mechanical interlock, shear forces can readily cause debonding.
• Primer‑induced barrier mechanism: The epoxy primer coats the polar sites on the titanium surface, preventing the penetration of water and oxygen into the interface, thereby inhibiting interfacial hydrolysis and titanium oxidation corrosion and enhancing moisture‑heat durability.

III. Application Scenarios

• Multi-material stator blades for aeroengines (core application scenario)

This article is directly aimed at the aviation sector. OGV Export‑oriented blade, with a titanium tip that bears the assembly loads and an intermediate carbon‑fiber composite for weight reduction—done in one step. RTM Co-injection molding replaces traditional segmented processing. +  Adhesive bonding reduces assembly defects and lowers the overall blade weight, meeting the lightweighting requirements of aerospace engines.

• Airframe / Titanium-Embedded Composite Load-Bearing Structure for Aircraft Wings

For hybrid composite components such as wing-to‑fuselage joints and fuselage stiffener frames, titanium inserts are used for bolted assembly. By employing the laser pre‑treatment one‑step forming process described herein, a secondary bonding step is eliminated, production line cycle time is shortened, and interfacial fatigue and hygrothermal resistance are enhanced.

• Aircraft Landing Gear Auxiliary Composite Component

Landing gear fairings, auxiliary load-bearing brackets, and titanium wear-resistant assembly areas. + Lightweight carbon‑fiber composite monolithic molding ensures that the interface remains delamination‑free under severe temperature‑cycling and salt‑spray service conditions.

• Hybrid Composite Shell for Space Launch Vehicles

One-step process for titanium flanges, embedded components, and carbon‑fiber composite cylindrical shells. RTM Molding simplifies tooling, reduces the risk of seal and delamination failures, and meets the aerospace industry’s requirements for lightweight design and high reliability.

• High-end hybrid load-bearing components for wind power and rail transit

Hybrid joints for wind turbine hubs and titanium‑embedded composite structures for railcar bodies can be manufactured at scale using a low‑cost sandblasting process, striking an optimal balance between interfacial strength and production‑line processing costs.

IV. Summary of the Article

(1) Core Research Findings

• Interfacial strength is due to mechanical interlocking. + Surface chemical activation jointly determines the outcome; plasma‑chemical activation alone cannot withstand shear loading, and joints subjected to pure plasma treatment exhibit complete debonding.
• Overall performance ranking (without primer): laser micro‑texturing > sandblasting > scouring pad > acid etching > plasma treatment (no bonding); laser shear strength is improved compared to pristine titanium. 221% , is the pinnacle of premium aviation craftsmanship;
• Epoxy primers slightly reduce the initial bond strength, but they are essential for sealing the interface and providing corrosion and damp‑heat resistance, making them indispensable for long‑life aerospace components.
• Pull-out tests serve only as a rapid preliminary screening; for aerospace load-bearing joints, the single-lap shear strength must be used as the primary acceptance criterion in process validation.

(II) Engineering and Technical Value

Traditional titanium composites are manufactured in a two-step process involving adhesive bonding and riveting, which is labor-intensive and results in significant weight gain; this paper demonstrates a one-step approach. RTM Feasibility of co-injection molding, with quantification. 5  Comprehensive interface data for mature industrial surface‑treatment processes are presented, along with two distinct process routes—one high‑cost and one low‑cost: laser micro‑texturing is selected for high‑end aircraft engines, while sandblasting is adopted for mass‑produced civilian components, thereby providing robust experimental support for the development of production‑scale process standards and quality‑inspection specifications for hybrid composite materials.

(3) Current Research Limitations

Only for 5 Grade titanium + RTM6 Epoxy systems, excluding high-temperature thermoplastics, BMI High-temperature‑resistant resins; only room‑temperature static shear testing has been conducted, with insufficient data on moisture‑heat exposure, thermal cycling, and interfacial durability under fatigue; no studies have yet been carried out on impact‑induced interfacial damage.

(4) Future Expansion Directions

• Expanding high-temperature aerospace resin systems ( PEEK , bismaleimide) compatible with titanium surface treatment processes;
• Conduct thermal cycling, salt spray, and cyclic fatigue aging tests to establish a durability reduction factor.
• Optimize the cost of laser micro‑texturing and develop a large‑area, low‑cost laser processing solution for titanium surfaces.
• Coupled simulation modeling, establishing surface roughness - An interface failure prediction model that supports the digital design of hybrid composite materials.

(5) Industry Insights

One-step method RTM Metal -  Co-curing of composite materials is the mainstream trend in aerospace lightweighting; however, interfacial delamination and debonding remain the primary bottlenecks to mass production. Relying solely on plasma activation cannot meet structural load‑bearing requirements, necessitating the use of laser treatment, sandblasting, or other methods to create micrometer‑scale mechanical anchoring structures. Balancing short‑term mechanical performance with long‑term environmental durability, aerospace components must adopt… “ Surface microtexture +  Epoxy primer ”  The integrated process balances high strength with full‑cycle service reliability.

Image and Text Guide

Figure 1. Ti-V Surface morphology of the material: (a) Titanium substrate; (b)Scotch-Brite Processing; (c) Sandblasting; (d) Plasma treatment; (e) Etching treatment; (f) Laser microtexturing.

Table 1. Roughness, surface free energy, and adhesion strength values under different surface treatment processes

Figure 2. Titanium plates with and without surface treatment (including those with primer and those without)

Figure 3. RTM Overall schematic diagram of the board (left) and SLS Schematic diagram of the sample (right).

Figure 4. Under different surface treatment conditions Ti-V of the SLS Test results.