Columnar Titanium Dioxide Growth via Segmented Firing
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Solution Overview
Problem
Existing methods for producing acicular titanium dioxide particles face limitations in achieving larger major-axis lengths and satisfactory particle size distributions, leading to insufficient anisotropic shape effects in applications such as electro-conductive materials and catalysts.
Innovation Solution
A process involving multiple stages of heating and firing with titanium dioxide nucleus crystals, an alkali metal source, and an oxyphosphorus compound to achieve columnar titanium dioxide particles with a weight-average major-axis length of 7.0-15.0 μm, where particles with a major-axis length of 10 μm or larger account for 15% or more, and subsequent reduction or nitriding reactions to produce low-order titanium oxide or titanium oxynitride with enhanced electro-conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a large amount of titanium compound is heated and fired at a time to produce particles with larger major-axis length, then the major-axis length increases, but alkali metal salt of titanic acid is produced causing insufficient growth and expansion of particle size distribution
Solution Approach 1:
The heating and firing process is divided into multiple stages rather than performing a single large-scale heating. The titanium compound is processed in sequential steps, allowing controlled growth at each stage while preventing the formation of alkali metal salt of titanic acid that causes poor particle size distribution.
Solution Approach 2:
Before the main heating and firing process, preliminary preparation steps are conducted including mixing the titanium compound with specific additives (such as organic compounds or other materials) that prevent the formation of alkali metal salt of titanic acid. This preliminary action ensures that when heating occurs, the titanium dioxide can grow properly without the harmful side effects.
2Productivity
If conventional heating and firing processes are used to produce acicular particles, then particles can be obtained, but fine particles of small major-axis length are produced in large proportion reducing the anisotropic shape effect
Solution Approach 1:
The heating temperature, holding time, and atmospheric conditions are optimized to promote preferential growth in the major-axis direction. By carefully controlling these parameters, the process produces particles with significantly larger major-axis lengths and more pronounced anisotropic shapes, enhancing the desired geometric characteristics.
Solution Approach 2:
Intermediary substances such as organic compounds or specific additives are introduced during the heating and firing process. These intermediaries facilitate the growth of acicular particles by providing a controlled environment that promotes anisotropic growth while suppressing the formation of fine spherical particles.
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 process results in titanium dioxide and titanium oxynitride particles with improved particle size distribution and electro-conductive properties, effectively utilizing their anisotropic shape for enhanced performance in electro-conductive materials, reinforcing materials, and catalysts.
Implementation Method 1
heating and firing of acicular titanium dioxide nucleus crystals, titanium source, alkali metal source and oxyphosphorus compound are carried out dividedly twice or more times
Implementation Method 2
when reducing reaction or nitriding reaction is effected using the above titanium dioxide, low-order titanium oxide or titanium oxynitride having columnar shape is obtained
Implementation Method 3
when reducing reaction or nitriding reaction is effected using the above titanium dioxide, low-order titanium oxide or titanium oxynitride having columnar shape is obtained
Data Source
AI summary
Titanium dioxide and an electro-conductive titanium oxide which each includes particles having a large major-axis length in a large proportion and comprises columnar particles having a satisfactory particle size distribution. A titanium compound, an alkali metal compound, and an oxyphosphorus compound are heated/fired in the presence of titanium dioxide nucleus crystals having an aspect ratio of 2 or higher to grow the titanium dioxide nucleus crystals. Subsequently, a titanium compound, an alkali metal compound, and an oxyphosphorus compound are further added and heated/fired in the presence of the grown titanium dioxide nucleus crystals. Thus, titanium dioxide is produced which comprises columnar particles having a weight-average major-axis length of 7.0-15.0 μm and in which particles having a major-axis length of 10 μm or longer account for 15 wt. % or more of all the particles. A solution of a tin compound and a solution of compounds of antimony, phosphorus, etc. are added to a suspension obtained by suspending the titanium dioxide. The particles are sedimented. Subsequently, the product obtained is heated/fired to produce an electro-conductive titanium oxide which comprises the titanium dioxide and an electro-conductive coating formed on the surface thereof.