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Industrial blades play a vital role in modern industrial manufacturing and processing. From paper and plastics to metals and even composites, blade performance has a direct impact on product quality and line efficiency. In addition to mechanical properties (such as hardness, toughness, strength, etc.), the chemical properties of the blade are equally critical, especially when operating in high-temperature, high-humidity, corrosive or abrasive environments.
In this article, we will systematically analyze the five key chemical characteristics of industrial blades, including material chemistry, corrosion resistance, oxidation resistance, coating chemical stability, and thermochemical stability, and analyze them in the context of real-world application scenarios, to help engineers, purchasers, and equipment maintainers more scientifically select and evaluate industrial blades.
Material Chemistry: Fundamental To Determining Chemical Stability
The most fundamental chemical properties of industrial blades derive from the chemical composition of the materials they are selected from. It can be said that the chemical formulation of the material not only determines the physical properties of the blade (e.g., hardness, strength, toughness), but also has a direct impact on its stability and longevity in wet, high-temperature, acidic, alkaline or oxidizing environments.
Impact Of Chemical Composition On Blade Performance
The role of different elements in the metal matrix varies widely. The key elements involved in the materials commonly used for blades are listed below:
C (carbon): Increases hardness, but also reduces toughness.
Cr (chromium): Forms a passivation film that improves corrosion resistance.
Mo (molybdenum): Improves corrosion and high-temperature resistance.
V (vanadium): Improves abrasion resistance and thermal stability, and refines grain size.
W (tungsten): Improves hot-hardness and high-temperature strength.
Co (cobalt): Used as a bonding agent in cemented carbide to increase crack resistance.
Ni (nickel): Improves impact and corrosion resistance.
Si (silicon): Increases Oxidation resistance, but too much will reduce toughness.
Comparison Of Chemical Composition Of Mainstream Blade Materials
Tungsten Carbide Blades
It’s mainly made of tungsten carbide (WC) particles sintered with cobalt (Co) bonding agent. WC shows very high stability in chemistry, resistant to most acid and alkali erosion, heat, corrosion and bonding resistance.
The higher the cobalt content, the greater the toughness but slightly less corrosion resistance; conversely, less cobalt is harder but more brittle.
Advantages: very high hardness, good chemical inertness, adaptable.
Disadvantages: brittle, easy to chip, high cost.
Scope of application: fiber materials, highly abrasive materials, high temperature and other harsh environments.
High-Carbon Steel Blades
High-carbon steel (e.g., SK5, T10A) generally has a carbon content of 0.6 to 1.0%, and its structure is simple, inexpensive, and highly machinable. But the chemical stability is weak, easy to rust or oxidize in the humid or acid gas containing environment.
Advantages: high hardness, low price.
Disadvantages: very easy to rust, not resistant to acids and alkalis, annealing failure at high temperatures.
Scope of application: general paper, wood cutting, plastic materials with low requirements.
Stainless Steel Blades
Common models such as 420J2, 440C, SUS316, etc., through the addition of 12 ~ 18% of chromium in the iron base to form a stable passivation film, and the further addition of molybdenum or nickel can enhance the resistance to pitting and stress corrosion resistance.
440C: high carbon content (about 1.2%), high chromium content, combining high hardness and medium corrosion resistance.
SUS316L: low carbon design, contains molybdenum, strong resistance to chloride corrosion, suitable for medical and food processing industries.
Advantages: rust resistant, food contactable, chemically inert.
Disadvantages: higher cost, not as hot hard as HSS.
High Speed Steel (HSS) And Powder Metallurgy High Speed Steel (PM-HSS)
Traditional HSS such as M2, M35, etc., contain a variety of alloying elements such as W, Mo, V, etc., with excellent wear resistance and hot hardness. Powdered HSS (e.g. ASP23, ASP60) further refine the carbide distribution on this basis to enhance corrosion resistance and homogeneity.
Advantages: high red hardness, can be reground many times, chemically insensitive.
Disadvantages: high price, medium corrosion resistance.
Scope of application: high-speed slitting, sheet metal, plastics, rubber and other medium and high strength materials cutting.
Ceramic Blades
Ceramic blades (such as Si₃N₄, Al₂O₃) have very high thermal stability and chemical inertia, almost no reaction in oxidizing, corrosive atmosphere, especially suitable for high temperature, dry cutting scenarios.
Advantages: very high thermal and chemical stability, long life, corrosion resistance.
Disadvantages: expensive, brittle, sensitive to vibration.
Scope of application: glass fiber, ceramics, electronic materials, aerospace composites processing, etc.
Logic Of Matching Blade Material Selection To Chemical Environment
Example 1: Pulp Or Wet Paper Cutting Line
Characteristics of the environment: Wet, containing alkaline bleach.
Recommended material: 440C stainless steel blade + TiCN coating.
Reason: Effectively prevent water vapor-induced corrosion while avoiding blade passivation.
Example 2: Lithium Battery Diaphragm Cutting
Environmental characteristics: extremely sensitive to the migration of metal ions, no precipitation of active substances required.
Recommended material: DLC-coated powdered steel or ceramic blade.
Reason: Ensure surface inertness and prevent contamination.
Example 3: Cutting Of Copper Foil, Aluminum Foil And Other Non-Ferrous Metals
Environmental characteristics: susceptible to galvanic corrosion with iron-based materials.
Recommended material: Use low cobalt content cemented carbide or corrosion-resistant powder steel.
Reason: Avoid contact reaction leading to dulling of the cutter or black spot corrosion.
Linkage Between Chemical Composition And Processing
In addition to its own chemical composition, the material’s chemical stability is also affected during smelting, heat treatment, sintering and other processes. For example:
Degassing: reduce non-metallic inclusions and improve corrosion resistance.
Low-temperature tempering: stabilize martensitic organization and avoid knife-edge temper brittleness.
High uniformity sintering: reduces sources of microcracks and improves overall blade life.
Therefore, evaluating the chemical performance of a blade cannot only be based on its material label, but also in conjunction with its process background, which is especially important in high-end precision machining. For more information on the blade manufacturing industry, see this article “The Detailed Guide To The Heat Treatment Process For Industrial Blades”.
The chemical composition of a blade is the source variable for chemical stability. Reasonable choice of material formulation can ensure that the blade will not be blunt, rusty or cracked in corrosive, high temperature, active substance contact and other working conditions. This is not only related to the life of the tool, but also affects the stable operation of the entire production line. Subsequent blades with appropriate coatings, structural design and mounting methods can elevate chemical stability to new heights.
Corrosion Resistance: Coping With Humid, Acidic Or Saline Environments
Corrosive factors are often present at industrial sites, such as moisture, acidic liquids, chloride ions, etc. If the blade material is not able to resist corrosion, it will lead to passivation of the cutting edge, rusting and even structural damage.
Corrosion Mechanisms And Effects
Corrosion is usually divided into chemical corrosion (such as sulfuric acid corrosion), electrochemical corrosion (such as salt water environment potential difference to form a battery reaction) and stress corrosion cracking. Blades exposed to corrosive media for a long period of time not only lose their cutting ability, but can also lead to flaky spalling of material layers, which greatly affects the stable operation of the equipment.
Materials And Corrosion Prevention Strategies
Stainless steel blades form a passivation film through chromium, which effectively prevents the formation of iron oxides.
Coated blades such as TiN, TiCN isolate the surface from chemical media and extend service life.
Plasticized blades or surface oxidation treatment can also play a protective role, suitable for occasions with high requirements on the surface.
In addition, specific blade types should be selected according to the actual chemical medium. For example, in chlorinated environments, it is recommended that 420 series stainless steel be avoided in favor of 316L or molybdenum enhanced stainless steel.
Antioxidant Performance: The Key To Non-Failure In High-Temperature Conditions
Oxidation is not limited to wet environments, but at high temperatures the blade metal reacts even more violently with oxygen. This is a fatal test for steel blades. If the oxidation resistance is insufficient, the blade will passivate or even flake off in a short time.
High-Temperature Oxidation Reaction
When the surface temperature of the blade exceeds 200°C, ordinary carbon steel begins to show surface oxidized skin (Fe₂O₃), and even begins to undergo structural annealing above 500°C, resulting in a decrease in hardness. High-alloy steels or carbide, on the other hand, maintain structural stability at higher temperatures.
Oxidation-Resistant Materials And Coatings
High-temperature alloys (e.g., Inconel, Hastelloy) have excellent high-temperature oxidation resistance, but are more costly.
Tungsten carbide’s oxidation resistance temperature up to 800 ° C or more.
AlTiN, TiAlSiN coatings possess excellent resistance to high-temperature oxidation and can withstand thermal shocks of about 850~1000°C or more.
Selecting a blade with excellent oxidation resistance is particularly suitable for high frequency, high load, dry cutting, or friction-heat-concentrated applications, such as slitting high-speed tapes, cutting glass fibers, and so on.
Chemical Stability Of Coatings: The Chemical Performance Of Blade Coatings
Coatings are not only the protective layer on the surface of industrial blades, but also a key factor in determining whether or not they can cope with complex chemical environments. The chemical stability of the coating material has a direct impact on the blade’s resistance to corrosion, heat and chemical attack.
The following from the coating type, characteristics, applicable scenarios and precautions in four aspects of sub-point description:
Common Coating Types And Their Chemical Stability
TiN (Titanium Nitride)
Characteristics: Golden yellow coating, high hardness, low coefficient of friction.
Chemical stability: good performance in neutral or weak acid environment, but not suitable for strong acid and alkali environment.
Application: suitable for general metal and plastic cutting, milder environment.
CrN (Chromium Nitride)
Characteristics: Good anti-adhesion, low coefficient of friction.
Chemical stability: can be used in food and pharmaceutical contact situations, with good chemical inertia.
Applications: food packaging, pharmaceutical films, adhesive tape industry.
DLC (Diamond Like Carbon Film)
Characteristics: Very high surface hardness, very low coefficient of friction, visually dark gray or black.
Chemical stability: excellent performance in strong acids and alkalis, salt spray, chlorides.
Applications: lithium batteries, circuit boards, electronic film materials, no metal migration sensitive occasions.
These are just three coatings briefly described, for more information about blade coatings, you can refer to this article “The Ultimate Guide To Blade Coating”.
Coating Stability Enhancement Of Blade Performance
Enhanced Corrosion Resistance: Prevents corrosive media such as water vapor, salts, acids and alkalis from attacking the substrate and extends the life of the blade.
Enhanced oxidation resistance: Avoid rapid failure of the blade in a high temperature oxygen environment, especially important for high speed dry cutting.
Enhanced surface inertia: Reduced adhesion to materials, reducing chip accumulation and knife sticking problems during processing.
Improved cutting cleanliness: the coating is stable and does not fall off, avoiding contamination of food, electronics, pharmaceuticals and other high-clean products.
Recommended Coatings For Different Application Environments
Humid Environments, Risk Of Mild Acid And Alkali Corrosion:
Recommended: TiCN, CrN
Description: Good chemical stability and surface inertness.
High Temperature Dry Cutting Or High Speed Slitting:
Recommended: AlTiN, AlCrN, AlTiSiN and other nano-coatings
Description：Still maintain hardness and stability in high heat environment, avoid oxidized delamination.
Food And Pharmaceutical Industries Or Where Metal Ion Precipitation Is Not Allowed:
Recommended: CrN or DLC
Description: Meets the requirements of food contact grade, chemically inert, does not contaminate the product.
Lithium Batteries, Circuit Boards, Photovoltaic Film Materials:
Recommended: DLC
Description: Diamond-like coating can completely avoid the release of active substances, combining high hardness and chemical stability.
Coatings not only enhance the surface of the blade, but are also the first line of defense against its chemical properties. The correct selection and use of highly stable coatings can effectively improve the adaptability of blades under complex working conditions, extend service life, reduce maintenance frequency, and ensure the cleanliness and consistency of processed products. Especially in the modern high-end manufacturing field, scientific selection of coatings has become an indispensable part of industrial blades.
Thermochemical Stability: A Durability Indicator For High Temperature And Chemistry
Real-world conditions are often multifactorial: high temperatures, acid gases, friction dust, water vapor etc. All of these place higher demands on blades in terms of thermochemical stability.
What Is Thermochemical Stability?
It means that when a blade is exposed to high temperatures, its material structure and surface chemistry remain in a stable state, including:
- No precipitation of harmful elements.
- No structural transformation (e.g. martensite to austenite).
- No chemical reaction with environmental media.
- No peeling or decomposition of the coating.
Examples Of Application Scenarios
PET film cutting: high speed friction generates high heat, while the residual additives often contain acidic components.
PCB cutting: the halogen elements in the dust react and corrode easily at high temperatures.
Lithium battery diaphragm cutting: the environment is extremely clean, and the blade cannot release any metal ions or active substances.
In this type of scenario, materials with high temperature inertia and high chemical inertia should be used, such as nitride ceramics, CBN or powdered steel blades equipped with DLC coating.
In real industrial applications, many blades fail not because they are dull or broken, but due to corrosion, oxidation, and chemical reactions that result in a degradation of structural properties. Therefore, in addition to hardness and toughness, the chemical properties of the blade should be taken into account. Reasonable matching of the chemical properties of the blade and processing conditions will significantly improve productivity, extend the life of the blade, reduce the frequency of equipment maintenance. This is precisely the high-end manufacturing environment, the core of industrial tool management.
