Powder clumping and unstable processing? It might be due to "moisture"—a comprehensive analysis of its influencing mechanisms.-2
The Impact of Moisture on Inorganic Powder Materials: Key Processes and Quality Control
Moisture, as a key variable in inorganic powder materials, has an impact far exceeding the simple concept of "dry or wet." It is a core factor profoundly affecting material properties, processing procedures, and even economic benefits.
I. Impact on Subsequent Processing
Dispersibility: In the processing of organic systems such as coatings, inks, and plastic masterbatches, moist powders are often difficult to disperse uniformly, easily producing particles or bubbles, thus affecting the gloss, mechanical strength, and durability of the finished product.
Sintering/Calcination Process: In the preparation of ceramics and refractory materials, powder moisture control is particularly critical. Uneven moisture distribution leads to inconsistent drying shrinkage, causing cracking; during high-temperature sintering, rapid evaporation of moisture may also lead to the formation of pores or cracks within the product.
Mixing Uniformity: When moist powders are mixed with other dry powder materials, agglomeration easily occurs, leading to uneven mixing and affecting the consistency of the material system.
II. Core Quality Control Indicators
Purity and Effective Content: Powder trade is usually priced by weight. Moisture, as an ineffective component, effectively "dilutes" the content of effective substances. For example, calcium carbonate with a nominal purity of 98% has an effective content of only 96.04% if its moisture content is 2%. Therefore, trade contracts usually specify a maximum moisture content (e.g., ≤0.5%).
Batch Stability: Fluctuations in moisture content directly affect the physical properties of powders (such as flowability and bulk density), significantly disrupting downstream continuous production. Maintaining a stable and low moisture content is crucial for consistent product quality.
III. Impact on Storage and Transportation
Caking and Deterioration: Highly hygroscopic powders (such as certain magnesium hydroxides and precipitated silica) may caking, harden, or even become ineffective during storage due to moisture absorption.
Packaging Corrosion: Moisture can corrode inner bags, ton bags, or metal packaging, causing packaging damage and material contamination.
Increased Transportation Costs: Moisture becomes an additional "ineffective transportation load," directly increasing logistics costs.
In summary, in the field of inorganic powder materials, moisture is essentially:
an "invisible process valve": profoundly regulating the physicochemical properties and processing performance of materials.
an "economic benchmark": directly related to the effective content of products and fair trade, serving as a key benchmark for measuring product quality and value.
