ISO 7692:1983

Overview

ISO 7692:1983 specifies a titrimetric method for determining the titanium content in ferrotitanium alloys. This standard is applicable to ferrotitanium containing titanium in the range of 20% to 80% by mass. Developed by ISO Technical Committee ISO/TC 132 for ferro-alloys, the method ensures accurate chemical analysis crucial for quality control and metallurgical applications.

The procedure involves dissolving the ferrotitanium sample using a combination of acids, separating interfering elements, reducing titanium ions, and then titrating with a standardized solution. Detailed instructions are provided for reagents, apparatus, sample preparation, and reporting. The document also includes illustrations of key equipment such as the Bunsen valve and a titration setup designed for use under an inert atmosphere.

Key Topics

• Scope and Applicability
  Applicable to ferrotitanium alloys with titanium between 20% and 80% by mass.

• Principle of the Method

  • Dissolution of the sample in sulfuric, hydrofluoric, nitric, and hydrochloric acids.
  • Separation of interfering metals (chromium, vanadium, molybdenum, tin) by precipitating titanium hydroxide in the presence of hydrogen peroxide.
  • Reduction of titanium to Ti³⁺ ions using metallic aluminum under nitrogen or carbon dioxide atmosphere.
  • Titration of Ti³⁺ using a standardized ferric ammonium sulfate solution, with ammonium thiocyanate as the indicator.

• Reagents and Preparation
  Use of analytical grade reagents including various acids (sulfuric, nitric, hydrochloric, hydrofluoric), sodium bicarbonate, hydrogen peroxide, sodium hydroxide, ammonium thiocyanate, and solutions of ferrous/ferric salts.

• Apparatus
  Laboratory glassware including PTFE beakers, conical flasks, a magnetic stirrer, Bunsen valves for inert gas atmosphere, and titration equipment optimized for nitrogen or carbon dioxide environments.

• Sample Handling
  Samples must be powdered to pass through a 160 µm sieve, prepared following ISO 3713. Accurate weighing and careful handling during acid digestion and titration ensure reliable results.

• Titration and Calibration
  Calibration of the ferric ammonium sulfate titrant is conducted using a titanium standard solution or titanium sponge. Rigorous controls such as blank tests and parallel sample analyses verify accuracy.

• Expression of Results
  Results are expressed as a percentage mass of titanium in the ferrotitanium sample, calculated using volumes of titrant consumed during the test and blank, sample mass, and calibration data.

Applications

This titrimetric method for titanium content determination is widely used in:

• Metallurgical Laboratories
  Quality control of ferrotitanium alloys to ensure correct titanium concentration for steelmaking and alloy production.

• Industrial Production
  Monitoring and verifying the composition of ferro-alloys in smelting and refining processes.

• Research & Development
  Analytical support for developing new ferrotitanium grades and refining alloy compositions.

• Regulatory Compliance
  Conformance testing according to international metallurgical standards for ferrotitanium products.

The method's accuracy and reproducibility make it valuable for any facility requiring standardized and reliable titanium quantification in ferrotitanium.

Related Standards

• ISO 3713: Ferro-alloys - Sampling and preparation of samples for chemical analysis - General guidelines.
• Standards related to ferro-alloy chemical analysis and metallurgical testing procedures.
• Other ISO methods for titanium and titanium alloy analysis, which may complement this titrimetric technique.

Keywords: ISO 7692, ferrotitanium, titanium content, titanium determination, titrimetric method, ferro-alloys chemical analysis, ferro-titanium testing, titanium assay, metallurgical testing standards, sample preparation, titration in inert atmosphere.