Multilayer CrN-CrON Coating for Plastic Processing Tools
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Solution Overview
Problem
Plastic processing tools face combined corrosive and abrasive wear due to interactions with plastics, particularly exacerbated by glass fiber reinforced plastics, necessitating coatings that provide both corrosion and abrasion resistance to extend tool life.
Innovation Solution
A multilayer coating system comprising chromium nitride (CrN) and chromium oxynitride (CrON) layers with modulated thickness ratios, specifically an under layer with thicker CrN layers and an upper layer with thinner CrN layers, deposited in a sequence such as CrN/CrON/CrN/CrON, to enhance both corrosion and abrasion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a multilayer coating with CrN and CrON layers is applied to provide both corrosion and abrasion resistance, then tool life is extended, but the coating complexity increases
Solution Approach 1:
The coating is divided into multiple alternating layers of CrN and CrON with different thickness ratios in different regions. This segmentation allows different portions of the coating to specialize in different functions - corrosion resistance or abrasion resistance - thereby extending tool life while managing overall coating complexity through functional specialization
Solution Approach 2:
The coating structure varies locally with different CrN/CrON layer thickness ratios in different regions. The under layer has thicker CrN layers for corrosion resistance, while the upper layer has thinner CrN layers for abrasion resistance. This local quality variation optimizes performance for specific operational requirements without requiring complete redesign of the entire coating system
2Reliability
If thicker CrN layers are used to improve corrosion resistance, then corrosion protection increases, but abrasion resistance decreases
Solution Approach 1:
Different regions of the coating have different CrN layer thicknesses tailored to their specific functional requirements. The under layer features thicker CrN layers localized for corrosion protection, while the upper layer has thinner CrN layers localized for abrasion resistance. This resolves the contradiction by applying appropriate thickness locally rather than uniformly throughout the entire coating
Solution Approach 2:
The coating is segmented into under layer and upper layer portions with distinct CrN thickness characteristics. This segmentation allows the corrosion resistance function to be optimized in the under layer while the abrasion resistance function is optimized in the upper layer, thereby satisfying both requirements simultaneously
3Strength
If thicker CrON layers are used to improve abrasion resistance, then wear protection increases, but corrosion resistance decreases
Solution Approach 1:
The coating structure implements local quality variation where CrON layer thickness is optimized for abrasion resistance in the upper layer while CrN layers provide corrosion resistance in the under layer. This localized optimization allows each material to excel at its primary function without compromising the other
Solution Approach 2:
The coating is segmented into functional zones where the upper layer emphasizes CrON for abrasion resistance and the under layer emphasizes CrN for corrosion resistance. This segmentation resolves the contradiction by assigning different thickness ratios to different functional zones rather than using a uniform structure
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 multilayer coating system significantly improves both corrosion and abrasion resistance, extending tool life by maintaining a high level of performance in plastic processing applications, as demonstrated by improved wear track depth and corrosion resistance tests.
Implementation Method 1
an under layer comprising at least one corrosion resistant material layer, preferably one or more AICrO layers as corrosion resistant layers
Implementation Method 2
an upper layer comprising one or more abrasion resistant material layers, preferably one or more CrON layers as abrasion resistant layers
Implementation Method 3
PVD coatings combining abrasive wear resistance and corrosion resistance are required
Data Source
AI summary
A multilayer coating exhibits good corrosion resistance and good abrasion resistance. The multilayer coating includes layers A and layers B deposited forming a sequence of the type . . . A/B/A/B/A . . . , with the layers A being CrN-based layers or CrN layers and the layers B being CrON-based layers or CrON layers. The multilayer coating exhibits a modulated ratio of the thicknesses of the A layers and B layers, in a manner that the multilayer coating comprises at least two different coating portions along the whole multilayer coating thickness, with differently adjusted ratio of the thicknesses of the A layers and B layers.