Zinc-Based Layer for Silver Coating Scratch Resistance

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Solution Overview

Problem

Silver-based metal layers in thermal insulation and solar protection glazing face issues with scratch resistance and resistivity degradation due to species migration during high-temperature heat treatments, particularly when certain dielectric and blocking layers are used, which affect both mechanical properties and optical performance.

Innovation Solution

Incorporating a zinc-based metal layer in contact with the silver layer, along with a blocking layer, to control the diffusion of metallic zinc elements during heat treatment, enhancing scratch resistance and mechanical properties while managing resistivity degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If blocking layers and dielectric layers containing zinc are used near the silver layer, then scratch resistance is improved, but resistivity degrades due to species migration during heat treatment

Engineering Contradiction:
Improvescratch resistanceVSAvoidresistivity
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

A zinc-based metallic layer is introduced as an intermediary between the silver functional layer and the blocking/dielectric layers. This intermediate zinc layer acts as a controlled diffusion source, allowing zinc species to migrate into the silver layer during heat treatment to improve scratch resistance, while the blocking layers prevent excessive migration that would degrade resistivity. The intermediary zinc layer mediates the interaction between the conflicting requirements of scratch resistance and resistivity maintenance.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention controls the thickness of the zinc-based metallic layer (0.1-10 nm) and the blocking layers (1-5 nm each) to optimize the balance between scratch resistance and resistivity. By precisely adjusting these dimensional parameters, the diffusion of zinc species into the silver layer is controlled to achieve improved mechanical properties without excessive degradation of electrical properties during heat treatment.

Inventive Principle:
Principle #35Parameter changes

2Strength

If high-temperature heat treatment is applied to the stack, then mechanical properties are improved, but the stack becomes more susceptible to scratches and species migration increases

Engineering Contradiction:
Improvemechanical propertiesVSAvoidscratch susceptibility
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The zinc-based metallic layer and blocking layers are deposited in advance before heat treatment, creating a pre-configured structure that will control species migration during the subsequent high-temperature process. The blocking layers are positioned and sized beforehand to prevent excessive zinc diffusion into the silver layer during heat treatment, while still allowing sufficient diffusion to improve scratch resistance. This preliminary structuring enables the heat treatment to proceed with improved mechanical properties without excessive scratch susceptibility.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the thickness of blocking layers is increased to control species migration, then resistivity degradation is reduced, but manufacturing complexity increases

Engineering Contradiction:
Improveresistivity controlVSAvoidstack structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention optimizes the thickness parameters of the blocking layers (1-5 nm each) to achieve effective control of zinc species migration while maintaining a practical number of layers. By carefully selecting these thickness parameters, sufficient control over resistivity degradation is achieved without unnecessarily increasing the number of layers or manufacturing complexity. The parameter optimization balances performance requirements with manufacturing feasibility.

Inventive Principle:
Principle #35Parameter changes

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 significantly improves scratch resistance and reduces hot and cold corrosion, though it may lead to some resistivity degradation, which can be mitigated by optimizing the thickness of the blocking layers or using additional absorbent layers.

Implementation Method 1

the migration of species during heat treatment. These changes affect not only the visual appearance but also the optical properties and electrical conductivity of the stack

Methodology Applied
Scientific EffectSpecies migration: Diffusion

Implementation Method 2

The presence of certain dielectric materials in the stack, particularly certain oxides, or certain blocking layers, promotes the migration of certain species, notably the release of metallic zinc elements near the silver layer, via the reduction of dielectric layers containing zinc

Methodology Applied
Scientific EffectReduction of dielectric layers: Reduction

Implementation Method 3

The presence of a blocking layer in contact with the silver layer seems to slow down the diffusion of metallic zinc through the silver layer and thus keep the metallic zinc elements in contact with the silver layer for longer

Methodology Applied
Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 4

The improved scratch resistance could be due to the doping of the silver layer with zinc

Methodology Applied
Scientific EffectDoping: Dopants

Data Source

PatentEP3880622B1Heat-treated material with improved mechanical properties
Publication Date: 2024.02.14 SAINT GOBAIN VITRAGE SA
  • EP3880622B1 patent drawingFigure 1(a)~1(d)
  • EP3880622B1 patent drawingFigure 2(a)~2(d)
  • EP3880622B1 patent drawingFigure 3(a)~3(f)

AI summary

The invention relates to a material comprising a transparent substrate coated with a stack of thin layers, said stack comprising at least one silver-based functional metal layer, at least one blocking layer which is in direct contact with a silver-based functional metal layer and at least one zinc-based metal layer which is located above or below said silver-based functional metal layer, and directly in contact therewith or separated therefrom by one or more layers, the total thickness of which is less than or equal to 20 nm.