Titanium Valve Nitrided Layer Wear Resistance
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Solution Overview
Problem
Internal-combustion engine valves, particularly those made of titanium, face significant wear issues due to high-speed operations, leading to limited durability and potential detachment of steel lash caps, which can cause engine damage. Existing solutions like acid treatment and plasma nitriding are limited by thickness, cost, and dimensional distortions.
Innovation Solution
A titanium valve with a nitrided layer formed by titanium nitrides (TiN) and aluminium-titanium nitrides (AlTiN2) up to 500 microns thick, achieved through laser remelting in a nitrogen-rich atmosphere, providing high hardness and wear resistance, replacing the steel lash cap with a single, durable part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a steel lash cap is used to improve wear resistance of the valve tip, then wear resistance is improved, but the risk of detachment and device complexity increases
Solution Approach 1:
The patent combines the valve body and valve tip into a single integrated titanium component, eliminating the separate steel lash cap assembly. The laser remelting process fuses the tip material directly to the valve body, creating a unified structure that maintains wear resistance while eliminating assembly complexity and detachment risks.
Solution Approach 2:
The patent uses a composite material approach by incorporating high-wear-resistance materials (such as tungsten carbide or ceramic composites) directly into the titanium valve tip through laser remelting. This creates a heterogeneous composite structure where the tip material provides wear resistance while the titanium body provides strength and weight reduction, all in a single integrated component.
2Reliability
If laser remelting is used to form a nitrided layer, then wear resistance and hardness are improved, but process complexity increases
Solution Approach 1:
The patent replaces traditional mechanical nitriding processes (such as plasma nitriding or chemical nitriding) with laser remelting technology. The laser provides localized, controlled heating that melts and rapidly solidifies the surface material in a nitrogen-containing atmosphere, forming a nitrided layer without the complexity of plasma generation or chemical bath systems.
Solution Approach 2:
The patent utilizes precise control of laser parameters (power, speed, focal position) and atmospheric composition (nitrogen concentration, pressure) to optimize the nitriding process. By adjusting these parameters, the process achieves deep nitride penetration (up to 500 microns) with controlled hardness gradients, balancing process complexity with treatment effectiveness.
3Length of stationary object
If conventional nitriding methods are used, then treatment depth is limited to 10-50 microns, but treatment time and cost increase
Solution Approach 1:
The laser remelting process employs periodic pulsed laser application, where the laser beam is applied in controlled pulses to the valve surface. This periodic energy input allows for progressive melting and rapid solidification cycles, enabling deep nitride layer formation (up to 500 microns) without requiring excessively long continuous treatment times, thus reducing overall processing time compared to conventional methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The nitrided layer offers superior wear resistance and durability, matching the performance of hardened steel valves while reducing weight, with surface hardness between 1100 HV and 2000 HV and nitride content of at least 50% by volume to a depth of 50 microns, enhancing the durability of the valve tip and reducing the risk of detachment.
Implementation Method 1
a nitriding process by laser remelting carried out in a nitrogen-rich atmosphere
Implementation Method 2
at least one region of the valve has a nitrided layer formed by titanium nitrides (TiN) and aluminium-titanium nitrides (AlTiN2)
Implementation Method 3
laser remelting in a nitrogen-rich atmosphere
Data Source
Figure 1~2
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AI summary
The present invention relates to a valve (1) for internal-combustion engines, in particular a titanium valve (1), in which at least one region of the valve (1) has a nitrided layer (10) formed by titanium nitrides and/or aluminium-titanium nitrides, that is up to 500 microns thick, with high surface hardness and high hardness through the depth of the thickness of the nitrided layer (10), providing the valve (1) with excellent wear resistance and high durability.