Variable Temperature Nano-Indentation via Gas-Mediated Cooling
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Solution Overview
Problem
Existing in-situ micro- and nano-indentation testing techniques under variable temperature conditions face limitations such as single-dimensional testing, uneven temperature loading, and inaccurate indentation depth measurements, which hinder the precise evaluation of materials' mechanical properties, especially for low-dimensional materials like thin films and coatings.
Innovation Solution
A traceable in-situ micro- and nano-indentation testing instrument and method that includes a vacuum or ambient chamber, macro-micro switchable mechanical loading modules, nano mechanical loading modules, optical positioning systems, and a contact or ambient mixed variable temperature module, enabling precise mechanical loading and temperature control, and in-situ monitoring of micro-zone mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If direct immersion of refrigerant is used for temperature loading, then continuous variable temperature can be achieved, but contact temperature drift of cold sources influences indentation depth measurement accuracy
Solution Approach 1:
The patent introduces a gas medium (inert gas) as an intermediary between the refrigerant and the sample. The refrigerant cools the gas, which then transfers heat to the sample through convection, eliminating direct contact between cold source and sample, thus avoiding temperature drift and condensation issues while maintaining continuous variable temperature loading capability
Solution Approach 2:
The patent employs a gas circulation system where refrigerated inert gas flows through a chamber to transfer cooling to the sample. This pneumatic heat transfer mechanism replaces direct thermal contact, enabling precise temperature control without the harmful effects of direct refrigerant immersion
2Object-affected harmful factors
If thermoelectric refrigeration without refrigerants is used, then no refrigerant contact is needed, but relatively low refrigerating power limits temperature loading range
Solution Approach 1:
The patent changes the refrigeration approach from direct contact (refrigerant immersion) or low-power thermoelectric to a gas-mediated convection system. This allows use of high-power refrigerants while avoiding their harmful direct contact with samples, achieving both strong cooling capability and elimination of refrigerant-sample interaction
3Device complexity
If modularized addition of temperature loading module is adopted, then equipment complexity is reduced, but displacement measurement errors caused by thermal expansion of indentation tip are not considered
Solution Approach 1:
The patent implements a feedback correction system that measures the thermal expansion of the indentation tip using a reference standard (e.g., silicon nitride tip) and automatically compensates for the displacement measurement errors. This maintains measurement precision while preserving the modularized equipment design
4Ease of manufacture
If room temperature calibration method is used, then calibration simplicity is maintained, but displacement measurement errors caused by thermal expansion of indentation tip are not corrected
Solution Approach 1:
The patent performs calibration at multiple temperature points before actual testing. By pre-calibrating the thermal expansion characteristics of the indentation tip at various temperatures and storing this data for compensation, the system achieves accurate measurements under variable temperature conditions while maintaining a simple calibration process at each temperature point
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 allows for accurate measurement of micro-zone mechanical properties, including hardness and Young's modulus, under various temperature conditions, supporting the study of material interactions and failure mechanisms, and providing a modular design for dynamic monitoring of materials with different dimensions.
Implementation Method 1
a laser interferometer probe assembly (1216) for measuring a displacement signal increment variation of the functional indentation tip (393)
Implementation Method 2
a refrigerating unit (1210, 1226) and a temperature control resistance wire (122, 1221) to form a continuously variable temperature loading environment through an inert gas
Implementation Method 3
a large-stroke pre-loading piezoelectric actuator (310) fixedly mounted on a first direct-current servo displacement driving platform (36)
Implementation Method 4
an MEMS micro force sensor (42) fixedly mounted at a tail end of a rigid connecting bar (43)
Data Source
AI summary
The present disclosure relates to a traceable in-situ micro- and nano-indentation testing instrument and method under variable temperature conditions. A macro-micro switchable mechanical loading module, a nano mechanical loading module and an indentation position optical positioning module are fixed on a gantry beam, an optical imaging axis of an optical microscopic in-situ observation or alignment module and a loading axis of the nano mechanical loading module are coplanar, the optical microscopic in-situ observation or alignment module and the function switchable module are mounted on a table top of a marble pedestal, and a contact or ambient mixed variable temperature module is fixedly mounted on the function switchable module. A modular design is adopted, the micro- and nano-indentation testing instrument is used as a core, in combination with a multi-stage vacuum or ambient chamber, an indentation depth traceability calibration module and multiple sets of optical microscopic imaging assemblies.