Aqueous Quenching Media Using Polymer Copolymers

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing quenching methods for metal substrates either result in excessive strain and warping with rapid cooling using water or inadequate hardening with slow cooling using oil, while aqueous polymer-based media face issues with polymer drag-out and viscosity changes.

Innovation Solution

An aqueous quenching medium concentrate comprising a mixture of non-ionic polyvinylpyrrolidone/polyvinylcaprolactam copolymer and poly(oxyethyleneoxyalkylene) glycol or vinylpyrrolidone polymer, which forms a stable coating that slows cooling rates similar to oil while preventing warping and cracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If water is used as quenching medium for rapid cooling, then cooling rate is improved, but metal substrate warps and cracks due to excessive strain

Engineering Contradiction:

Improvecooling rateVSAvoidmetal substrate integrity

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The patent uses an aqueous polymer solution as an intermediary quenching medium between water and oil. The polymer coating that forms on the metal substrate surface acts as a mediator that moderates heat transfer, providing a cooling rate between water and oil while preventing excessive strain and distortion.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical and chemical parameters of the quenching medium by adding polymers to water. This creates an aqueous polymer solution with specific viscosity and thermal properties that provide controlled cooling rates, preventing both excessive strain from water and inadequate hardening from oil.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If hydrocarbon oil is used as quenching medium for slower cooling, then metal substrate ductility is improved, but metal substrate fails to adequately harden

Engineering Contradiction:

Improvemetal substrate ductilityVSAvoidmetal substrate hardness

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The patent modifies the thermal properties of the quenching medium by using aqueous polymer solutions with controlled concentration and molecular weight. This achieves cooling rates that are slower than water but faster than oil, enabling both ductility and adequate hardening of the metal substrate.

Inventive Principle:

Principle #35Parameter changes

3Speed

If aqueous polymer-based quenching media with large amounts of polymer are used, then cooling rate control is improved, but polymer drag-out occurs and viscosity changes requiring additional washing

Engineering Contradiction:

Improvecooling rate controlVSAvoidpost-quenching processing

Core Design Contradiction:

SpeedVSEase of operation

Solution Approach 1:

The patent optimizes polymer concentration to low levels (0.005-10% by weight) and selects specific molecular weights and types that provide adequate cooling rate control without excessive drag-out. This balance allows effective quenching while minimizing the need for additional washing operations.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite quenching media containing multiple polymer types or combinations of polymers with inorganic salts. These composite formulations provide synergistic effects that improve cooling rate control while reducing polymer drag-out and viscosity changes compared to single-polymer systems.

Inventive Principle:

Principle #40Composite materials

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 quenches metal substrates without warping or cracking, achieving a balance in cooling rate and hardness, with reduced wastewater treatment needs and environmental impact.

Implementation Method 1

US Patent No. 4,087,290 discusses an aqueous quenching medium containing a water-soluble polyacrylate, such as a sodium polyacrylate, which forms a vapor blanket about the metal substrate during the quenching operation.

Methodology Applied

Scientific EffectVapor blanket formation: Evaporation

Implementation Method 2

The polymer layer that coats the metal permits relatively short quenching times, thereby resulting in minimum internal stress of the metal substrate, minimum distortion of the metal substrate, and imparts uniform hardenability of the metal substrate.

Methodology Applied

Scientific EffectPolymer coating formation: Adsorption

Implementation Method 3

The cooling step, which is known in the art as 'quenching', typically is performed rapidly and is accomplished by immersing the hot metal substrate in a liquid quenching medium

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP2215177B1Aqueous quenching media and use therof in quenching metal substrates

Publication Date: 2018.10.10 HOUGHTON TECHNICAL CORP

AI summary

Aqueous media for quenching metal substrates are provided and contain (i) a polyvinylpyrrolidone/polyvinylcaprolactam copolymer and (ii) one or more of a second polymer, which is selected from (a) a substituted oxazoline polymer; (b) a poly(oxyethylene-oxyalkylene) glycol; or (c) a polyvinylpyrrolidone polymer. The quenching bath provides reduced cooling rates through the martensite temperature ranges. Also provided are processes for quenching metal substrates using these quenching media.