Lithium Borate Crucible Liner for XRF Sample Protection
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Solution Overview
Problem
Highly reactive materials pose a risk of exothermic reactions with platinum crucibles during XRF sample preparation, leading to damage and requiring hazardous handling procedures.
Innovation Solution
A free-standing lithium borate crucible liner is formed to protect the platinum crucible, allowing the sample to be heated without reacting with the liner until the flux dissolves the oxidized sample, using a two-part mould and a two-stage firing process to create a self-supporting, pure lithium tetraborate liner with particles less than 100 μm in size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a platinum crucible is used directly with highly reactive samples, then the crucible is damaged by exothermic reactions, but using a protective liner adds manufacturing complexity
Solution Approach 1:
The crucible system is divided into two functional parts: the platinum crucible providing thermal stability and the removable lithium borate liner providing chemical protection. This segmentation allows each component to perform its specialized function while maintaining overall system reliability.
Solution Approach 2:
The lithium borate liner acts as an intermediary barrier between the highly reactive sample and the platinum crucible. It prevents direct contact and exothermic reactions while allowing heat transfer, thus protecting the crucible without compromising the heating function.
2Ease of manufacture
If flux is placed in the crucible before heating, then the sample can dissolve properly, but the flux reacts with the platinum crucible at high temperatures
Solution Approach 1:
The lithium borate liner serves as a protective intermediary that prevents the flux from reacting with the platinum crucible wall during heating. The liner is positioned between the flux-sample mixture and the crucible, blocking harmful chemical interactions while allowing the dissolution process to proceed.
Solution Approach 2:
The lithium borate liner is designed as a consumable component that is replaced after each use. It protects the expensive platinum crucible from damage by flux reactions, and once depleted or contaminated, the liner is discarded rather than the crucible.
3Reliability
If the crucible is rotated outside the furnace to cool the flux surface, then a glassy flux surface forms to protect the crucible, but the procedure becomes dangerous and difficult to perform
Solution Approach 1:
The lithium borate liner is pre-formed and placed in the crucible before heating begins. This preliminary protective layer eliminates the need for subsequent dangerous manual rotation operations to cool the flux surface, as the liner already provides the necessary protection from the start.
Solution Approach 2:
The invention converts the previously harmful direct contact between hot flux and platinum crucible into a beneficial protected interface. The lithium borate liner intentionally allows controlled interaction between flux and liner material, creating a protective glassy layer on the liner itself rather than requiring dangerous manual cooling procedures.
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
This method enables safer and easier XRF sample preparation by preventing crucible damage and allowing for effective dissolution of samples in the flux, suitable for a wide range of materials, while maintaining the structural integrity of the liner.
Implementation Method 1
raising the temperature of the sample in the crucible to a fusing temperature at which the lithium borate liner acts as a flux and dissolves the oxidised sample
Implementation Method 2
The crucible with the liner and sample is placed in a furnace and heated to a temperature sufficient to heat the liner and sample to the fusing temperature
Data Source
AI summary
A method of of preparing samples for XRF using a flux and a platinum crucible includes forming the flux into a free-standing crucible liner. This may be achieved by mixing lithium borate particles with a liquid to form a paste; placing the lithium borate paste onto the inner surface of a mould; and after drying removing from the mould and firing the lithium borate paste to dry the lithium borate to form a free-standing crucible liner. The liner may be placed within a platinum crucible and then a sample placed in the liner. The temperature of the crucible is raised to a sufficient temperature that any oxidation reaction takes place before taking the temperature above the melting temperature of the flux to melt the crucible liner and dissolve the sample into the flux. The crucible can then be cooled and XRF measurements made on the sample.