Division 01 — Metallurgical / Non-Ferrous / Copper / Degassing
Degassing Tablet
Dissolved hydrogen is the primary cause of gas porosity in copper alloy castings. Hydrogen enters the melt from moisture in the charge material, from wet or damp crucibles, and from atmospheric humidity during the melting and holding cycle. At pouring temperature, the metal holds the hydrogen in solution; as the casting solidifies and the solubility drops sharply, the hydrogen precipitates as gas bubbles — producing gas porosity distributed through the casting cross-section. For pressure-rated castings such as pump impellers, valve bodies, and marine bronze fittings, gas porosity is a direct rejection cause under hydrostatic testing. EGYTAB CU copper degassing tablets from CFC Egypt provide a simple, reliable, and consistent method for removing dissolved hydrogen from the melt immediately before each pour. The pre-measured tablet format eliminates the dosing variability of hand-added granular degassing agents, and the plunging method ensures complete distribution of the degassing reaction through the full melt volume. EGYTAB CU is manufactured at our Sadat City plant and is used in both induction furnaces and oil- or gas-fired crucible furnaces.
Copper and its alloys are among the most reactive metals in common foundry use. Molten copper oxidises rapidly on contact with atmospheric oxygen, forming cuprous oxide (Cu2O) that disperses throughout the melt and, if not removed, casts as non-metallic inclusions that reduce mechanical properties and block porosity testing. In brass, zinc evaporation from the melt surface above 950 °C causes surface porosity, composition drift, and white fume that is a health and housekeeping concern. CFC Egypt's EGYFLUX CU copper flux range — four grades covering the full spectrum of copper alloy types and melting temperatures — addresses these problems at source. Applied as a powder or granule to the melt surface, EGYFLUX CU fluxes melt and spread to form a continuous protective barrier that prevents oxidation, coalesces dispersed oxide into a skimmable slag layer, and actively suppresses zinc vapour loss in brass melts. All four grades are manufactured at our Sadat City plant.
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Ce qu'il couvre
EGYTAB CU addresses the complete degassing requirement for copper and copper-alloy melts — from the mechanism of hydrogen removal through to application method and use in combination with EGYFLUX CU copper fluxes.
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How EGYTAB CU Works
EGYTAB CU is plunged to the base of the melt using a preheated steel rod. On contact with the molten copper alloy, the tablet decomposes and releases gas that forms fine bubbles distributed throughout the bath. These bubbles rise through the melt and collect dissolved hydrogen by diffusion as they ascend, carrying it to the melt surface where it escapes. The result is a melt with substantially reduced dissolved hydrogen content, which solidifies without the gas porosity caused by hydrogen precipitation during solidification.
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Pre-Measured Dosing Consistency
Each EGYTAB CU tablet contains a precisely measured quantity of degassing compound for a defined melt weight. The pre-measured format eliminates the variability of hand-added powder or granule — under-dosing leaves residual hydrogen that causes porosity; over-dosing causes excessive gas evolution and melt splashing. Consistent tablet dosing allows gas porosity to be controlled as a process parameter rather than left to chance, and the number of tablets per heat can be documented as part of the casting process record.
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Induction & Crucible Furnace Compatibility
EGYTAB CU is formulated for use in both induction and oil- or gas-fired crucible furnaces. In induction furnace applications, electromagnetic stirring assists the distribution of degassing bubbles through the melt. In crucible furnaces, the tablet is plunged using a preheated rod and held at depth for the full degassing reaction time before withdrawal. The plunging rod must be preheated to avoid introducing moisture — the source of the hydrogen the treatment is designed to remove.
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Use with EGYFLUX CU Covering Flux
Degassing and flux covering address two distinct but related aspects of copper melt quality. EGYFLUX CU covering flux prevents surface oxidation and captures oxide impurities throughout the melt cycle. EGYTAB CU removes dissolved hydrogen immediately before the pour. Both treatments are necessary for castings that must be both oxide-inclusion-free and gas-porosity-free. The standard sequence is: flux throughout the melt and hold; skim the flux-slag layer before degassing; plunge EGYTAB CU; allow reaction to complete; pour. Contact our technical team for the correct combined treatment procedure for your alloy and furnace type.
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Domaines d'utilisation
EGYTAB CU degassing tablets are used in every application where copper alloy castings must be free of gas porosity — which is the requirement for all pressure-rated and structurally critical copper castings.
Marine Bronze — Pressure-Tight Castings
Marine propellers, sea valves, through-hull fittings, and pump casings in tin bronze and aluminium bronze must be free of gas porosity throughout their cross-section. A single gas void in a sea valve or hull fitting below the waterline is a serious defect. Marine classification societies require documented melt treatment — including degassing — as part of the casting certification process. EGYTAB CU degassing before every pour is standard practice in bronze foundries producing to classification society requirements.
Valves & Pump Casings
Bronze and brass pump casings, valve bodies, and fittings for water, gas, and chemical service are pressure-tested to rejection criteria that include any porosity that allows leakage. Gas porosity — caused by dissolved hydrogen in the melt — is one of the two principal causes of hydrostatic test failure in copper alloy castings, alongside oxide inclusions. Degassing with EGYTAB CU on every heat eliminates gas porosity as a defect variable, allowing the foundry to focus quality control on other variables in the casting process.
Phosphor Bronze Bearings & Bushings
Phosphor bronze and gunmetal bearings and bushings must have sound internal structure — gas porosity beneath the bearing surface acts as a stress concentration and initiates fatigue failure under the cyclic loading of bearing service. For centrifugally cast bearing tubes, gas porosity that breaks through to the bore surface creates machining voids that reduce the effective bearing area and accelerate wear. EGYTAB CU degassing is specified for bearing tube and bushing production where internal soundness standards are applied.
Electrical & High-Conductivity Copper
High-conductivity copper castings for electrical applications — busbars, switch contacts, and electrode holders — require dense, pore-free metal throughout the section. Gas porosity in electrical copper reduces cross-sectional area and increases resistance at the void location, creating localised heat generation under load. For copper-chromium and copper-zirconium alloys used in high-current contact applications, proper degassing treatment is essential for achieving the conductivity and mechanical properties required by specification.