Lead-Calcium-Tin Grid Lattice Constant Control
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Solution Overview
Problem
Conventional methods for producing lead acid battery grids with lead-calcium-tin alloys struggle to achieve sufficient corrosion resistance due to the segregation of tin and calcium atoms during the extrusion process, resulting in a heterogeneous structure and inadequate lattice constant for improved corrosion and fatigue strength.
Innovation Solution
A positive electrode grid is produced using a lead alloy with a calcium content of 0.10 mass % or less and a tin content of 2.3 mass % or less, obtained through continuous slab casting and multistage rolling, which allows for a lattice constant of 4.9470 Å or less, enhancing corrosion resistance and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous casting is used to produce lead-alloy sheet, then production efficiency is improved, but the alloy develops a double layer structure with insufficient corrosion resistance and fatigue strength
Solution Approach 1:
The invention changes the chemical composition parameters of the lead alloy by strictly controlling calcium content to 0.03-0.10 mass% and tin content to 1.5-2.3 mass%, which modifies the alloy's microstructure and significantly improves corrosion resistance while maintaining the efficiency of continuous casting production
Solution Approach 2:
The invention creates a composite lead alloy system combining lead, calcium, and tin elements where calcium provides structural strength and tin provides corrosion resistance, achieving synergistic effects that resolve the contradiction between production efficiency and corrosion performance
2Reliability
If tin content is increased to improve corrosion resistance, then corrosion resistance is enhanced, but manufacturing cost increases due to tin being more expensive than lead
Solution Approach 1:
The invention optimizes the tin content parameter to a specific range of 1.5-2.3 mass%, which is sufficient to achieve the required corrosion resistance (lattice constant ≤4.9470 Å) while avoiding excessive tin addition that would unnecessarily increase manufacturing costs
Solution Approach 2:
The invention applies tin selectively at the optimal concentration level (1.5-2.3 mass%) where it provides maximum corrosion resistance benefit per unit cost, rather than uniformly high tin content throughout the alloy, achieving cost-effective corrosion protection
3Ease of manufacture
If extrusion process is used to produce lead-alloy sheet, then manufacturing flexibility is improved, but tin and calcium atoms segregate resulting in heterogeneous structure and inadequate lattice constant
Solution Approach 1:
The invention adjusts the chemical composition parameters (Ca: 0.03-0.10 mass%, Sn: 1.5-2.3 mass%) to ranges that promote homogeneous atom distribution in the alloy, preventing segregation during extrusion and achieving the required lattice constant of ≤4.9470 Å
Solution Approach 2:
The invention preemptively controls the alloy composition before extrusion to prevent segregation, by setting calcium and tin content within specific ranges that ensure homogeneous mixing and stable solid solution formation, counteracting the segregating tendency that would otherwise occur during the extrusion process
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 approach significantly improves the corrosion resistance and deformation suppression of the positive electrode grid, maintaining cost-effectiveness by optimizing the tin content within the alloy's solid-solubility limit, thereby extending the cycle life of lead acid batteries.
Implementation Method 1
continuous slab casting, from a molten lead alloy containing calcium and tin
Implementation Method 2
rolling the lead-alloy slab by multistage rolling, to obtain a lead-alloy sheet
Data Source
AI summary
An objective is to improve the corrosion resistance of a positive electrode grid for lead acid batteries.Provided is a positive electrode grid for lead acid batteries, and a lead acid battery including the grid. The grid includes a lead alloy containing calcium and tin. The lead alloy has a calcium content of 0.10 mass % or less, and a tin content of 2.3 mass % or less, and a lattice constant of 4.9470 Å or less.