Nip Roller DLC Coating to Prevent Surface Defects
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Solution Overview
Problem
Rollers used in film formation, such as nip and calender rollers, face challenges with surface defects and damage from contaminants due to contact fatigue, which affects the quality of the films and products, and conventional hardening methods like jet spraying tungsten carbide and electroplating chromium have micrometer scale defects.
Innovation Solution
The application of a hardening layer formed by chemical vapor deposition (CVD) or plasma-assisted chemical vapor deposition (PACVD) of diamond-like coatings (DLC) and physical vapor deposition (PVD) of tungsten carbide on rollers to increase their hardness and prevent damage from contaminants, with optional underlayers of tungsten carbide, copper, or chrome for enhanced protection and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional hardening methods like jet spraying tungsten carbide or electroplating chromium are used, then the roller surface hardness is increased, but micrometer scale defects such as pinholes are introduced
Solution Approach 1:
The patent replaces conventional mechanical hardening methods (jet spraying, electroplating) with a chemical vapor deposition process. The DLC coating is deposited through CVD where carbon-containing gas decomposes on the roller surface to form a dense, defect-free diamond-like carbon layer, eliminating the micrometer-scale defects inherent in mechanical application methods
Solution Approach 2:
The patent applies a composite structure consisting of multiple layers: an intermediate layer (such as copper or chrome) deposited first, followed by the DLC hardening layer. This multi-layer composite approach provides both adhesion to the substrate and a defect-free hard surface, resolving the contradiction between hardness and surface quality
2Reliability
If roller surface hardness is increased to prevent damage from contaminants, then contact fatigue resistance is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent replaces complex mechanical hardening processes with chemical vapor deposition, which provides a more controlled and consistent coating application. The CVD process automatically forms a uniform DLC layer with inherent stress resistance, reducing the need for additional mechanical processing steps and simplifying the overall manufacturing workflow
Solution Approach 2:
The patent utilizes parameter changes in the CVD process, specifically controlling temperature and gas composition, to optimize the DLC coating properties. By adjusting these parameters, the process achieves optimal hardness and contact fatigue resistance while maintaining process simplicity and repeatability
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 solution effectively increases the rollers' hardness, reducing surface defects and contact fatigue, thereby improving the quality and durability of the films and products by providing a robust and uniform surface resistant to high pressures and contaminants.
Implementation Method 1
a hardening layer formed by one of chemical vapor deposition (CVD) or plasma assisted chemical vapor deposition (PACVD) of diamond like coating (DLC)
Implementation Method 2
a hardening layer formed by one of chemical vapor deposition (CVD) or plasma assisted chemical vapor deposition (PACVD) of diamond like coating (DLC)
Implementation Method 3
physical vapor deposition (PVD) of tungsten carbide
Data Source
AI summary
The present disclosure relates to rollers such as nip rollers and calendering rollers with a coating and a method of applying the coating. More specifically, the present disclosure relates to a nip roller or a calender roller with a hardening layer applied to the surface to prevent damage from contaminants.