New High Quality Diesel Nozzle DLLA150P77 for Injection Nozzle Diesel Engine Parts

Abstract
With the continuous increase of injection pressure and combustion temperature in modern diesel and gasoline direct injection engines, traditional steel-based injector nozzles are increasingly challenged by thermal deformation, oxidation, and wear. Silicon carbide (SiC)-based composite materials, characterized by high hardness, excellent thermal stability, and superior corrosion resistance, have become a promising candidate for high-performance injector nozzles. This paper investigates the high-temperature structural stability and fuel spray characteristics of SiC-based composites through theoretical analysis, computational simulation, and experimental validation.

1. Introduction
The injector nozzle plays a crucial role in determining atomization quality, fuel distribution, and combustion efficiency. Under extreme thermal and mechanical conditions, conventional metallic nozzles may suffer from microstructural degradation and erosion, leading to reduced spray precision. SiC-based composites, reinforced with fibers or nanoparticles, provide excellent mechanical strength at temperatures exceeding 1000°C, along with low thermal expansion and outstanding chemical inertness. These properties make them ideal for next-generation injector designs.

2. High-Temperature Stability Analysis
The high-temperature stability of SiC-based composites primarily depends on their matrix–reinforcement interface and oxidation behavior.

• Thermal Stability: Experimental thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) show negligible mass loss and minimal thermal expansion up to 1200°C.

• Mechanical Retention: Finite element thermal–mechanical simulations reveal that SiC-based nozzles maintain over 90% of their room-temperature strength under 800°C operating conditions, whereas traditional tool steel degrades by more than 30%.

• Oxidation Resistance: The formation of a protective SiO₂ film on the surface effectively inhibits further oxidation, ensuring dimensional stability and long-term durability under cyclic thermal loads.

3. Spray Performance Evaluation
The superior thermal and mechanical stability of SiC composites contributes to more consistent spray characteristics:

• Spray Cone Angle and Penetration: High stiffness and low thermal deformation preserve the designed geometry of nozzle holes, leading to a stable spray cone angle and improved fuel atomization.

• Droplet Size Distribution: Computational Fluid Dynamics (CFD) simulations indicate a 5–10% reduction in Sauter Mean Diameter (SMD) compared with conventional steel nozzles, promoting finer fuel dispersion and enhanced combustion efficiency.

• Coking and Fouling Resistance: The chemical inertness and smooth surface finish of SiC-based materials reduce carbon deposition at the nozzle tip, prolonging service intervals and maintaining spray uniformity.

4. Conclusions
Silicon carbide-based composite materials demonstrate remarkable advantages in both high-temperature stability and spray performance for injector nozzle applications. Their superior thermal resistance, mechanical strength retention, and anti-coking properties enable more stable and efficient fuel atomization under extreme engine conditions. Future work should focus on optimizing microstructural design, exploring hybrid SiC–metal matrix composites for improved toughness, and integrating additive manufacturing technologies to achieve complex nozzle geometries and cost-effective mass production.