Double-Coated Expansion Anchor for Alkaline Corrosion Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Anchor bolts used in cracked concrete face challenges with atmospheric corrosion and tribological properties, especially in outdoor environments where wet concrete creates an alkaline environment that can degrade zinc and zinc-nickel coatings, leading to delamination and reduced performance.
Innovation Solution
A double coating comprising a zinc flake or aluminum flake top layer over a hot dip galvanized zinc, ZnNi, or ZnFe base layer on a carbon steel substrate, providing both corrosion protection and tribological properties, which maintains performance in alkaline conditions and withstands mechanical loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a thin tribological coating is applied on top of Zn/Ni or Zn/Fe electroplated carbon steel, then tribological properties for cracked concrete operation are improved, but corrosion protection in alkaline wet concrete environment deteriorates due to coating attack and delamination
Solution Approach 1:
The patent applies a composite coating system consisting of multiple layers: a base layer (Zn, Zn/Ni, or Zn/Fe electroplating or hot-dip galvanizing) combined with a top layer (zinc flake coating, aluminum flake coating, or hybrid flake coating). This composite structure combines the corrosion protection capabilities of the base layer with the enhanced chemical stability and alkaline resistance of the flake coating top layer, while maintaining necessary tribological properties for cracked concrete operation.
Solution Approach 2:
The patent modifies the coating composition by introducing flake-based coatings (zinc flake, aluminum flake, or hybrid) as the top layer. These flake coatings have different chemical and physical parameters compared to conventional thin tribological coatings, providing superior resistance to alkaline attack from wet concrete while maintaining adequate tribological performance.
2Reliability
If stainless steel is used instead of Zn/ZnNi coated carbon steel, then corrosion resistance in alkaline concrete environment is improved, but manufacturing expenses increase
Solution Approach 1:
The patent creates a cost-effective alternative to stainless steel by developing a composite coating system on carbon steel substrates. The base layer provides initial corrosion protection, while the flake coating top layer (zinc flake, aluminum flake, or hybrid) delivers enhanced alkaline resistance comparable to stainless steel, but at lower manufacturing cost since it can be applied to conventional carbon steel rather than requiring expensive stainless steel material.
3Reliability
If a double coating with zinc flake and/or aluminum flake top layer is applied, then durability and corrosion resistance in wet concrete and atmospheric conditions are improved, but device complexity increases
Solution Approach 1:
The patent implements a multi-layer composite coating where the base layer (electroplated or hot-dip galvanized) and the flake coating top layer work synergistically. The base layer provides foundational corrosion protection and adhesion, while the flake top layer provides enhanced chemical stability and alkaline resistance. This composite approach achieves superior durability through material composition rather than mechanical complexity.
Solution Approach 2:
The patent simplifies the overall system by modifying coating parameters and composition rather than adding mechanical protection systems. By changing from single-layer to multi-layer coating architecture with specific material properties (flake structure, metallic composition), the patent achieves enhanced durability without significantly increasing device complexity.
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 double coating enhances durability and reliability of anchor bolts in cracked concrete, offering superior corrosion resistance and tribological properties without the need for additional coatings, allowing carbon steel to be used effectively in outdoor applications.
Implementation Method 1
Being a stable polymer-based corrosion protection coating with metallic flakes, it can provide both sacrificial properties and chemical stability
Implementation Method 2
the base layer is a hot dip galvanized zinc layer, a ZnFe layer or a ZnNi layer, in particular an electroplated ZnNi layer, or an electroplated ZnFe layer
Implementation Method 3
the base layer is a hot dip galvanized zinc layer, a ZnFe layer or a ZnNi layer
Implementation Method 4
Being a stable polymer-based corrosion protection coating with metallic flakes, it can provide both sacrificial properties and chemical stability, preferably against alkaline attack in wet concrete environments
Implementation Method 5
the relatively high hardness of the ZnNi, ZnFe or HDG base layer can mechanically stabilize the top layer, in particular under high loads experienced at the expansion mechanism
Data Source
Figure 1~4
AI summary
The invention relates to an expansion anchor having an anchor bolt, an expansion sleeve, as a first element, wherein the expansion sleeve surrounds the anchor bolt, a wedge body, as a second element, for expanding the expansion sleeve, wherein the wedge body is provided on the anchor bolt, and a double coating that is provided on one of the first and second elements at least in an area of contact with the other of the first and second elements, wherein the element, on which the double coating is provided, is a carbon steel part. According to the invention, the double coating comprises a zinc flake and/or aluminium flake top layer and a hot dip galvanized zinc, a ZnFe or a ZnNi base layer that is covered by the zinc flake and/or aluminium flake top layer.