The study on the possible use of microgranite in glazed porcelain tile bodies as an alternative fluxing agent

Alternatif bir ergitici olarak mikrogranitin sırlı porselen karo bünyelerde kullanım olanaklarının araştırılması

Abstract

The ceramic tile industry is being progressively moving its worldwide production toward new material with improved aesthetic and technical properties, e.g. glazed porcelain tiles that are able to successfully compete with ornamental stones and other building products. Porcelain tiles thanks to their superior properties such as whiteness, mechanical and frost resistance, low water absorption etc. attracted the attention of ceramic tile producers, causing the researches in this area to start in 80’s. Today the porcelain tiles are divided into three main groups; natural, polished and glazed porcelain tiles. Porcelain tiles usually posses water absorption of less than 0.5% but in many cases it is less than 0.01%, excellent wear resistance and high breaking strength which make them high-tech products. Moreover easily cleanable and anti-slip surfaces widen their applications both in business and home residences. They can be produced in either way; glazed or unglazed, coloured with traditional stains and fired at 1200-1220 ºC for 40-80 min. Porcelain tile is a highly vitrified ceramic material produced from a body formulated by mixtures of clay, quartz and sodium-potassium feldspar in which vitrification indicates a high degree of melting on firing which confers low porosity and high glass content. Feldspar minerals are essential components in igneous, metamorphic and sedimentary rocks, amongst the numerous rocks in which they are present. Feldspar minerals are essential components in igneous rocks as granite, which contains up to 50% or 70% of alkaline feldspar. Granite, however is rarely used for its feldspathic content. Rather a whole range of rocks geologically connected to granite is preferred. In this study, microgranite samples were collected from a large ceramic production region in Karaköy located in the Southeast part of Bilecik province in Turkey (NW Turkey). Due to its high alkaline (Na2O + K2O ≈ 8.0-8.5) and low Fe2O3, TiO2 content, it is likely to consider microgranite as a fluxing agent for porcelain tile bodies. The XRD pattern taken from the as-received microgranite raw material revealed the fact that the samples consisted of quartz (SiO2), albite, sanidine, muscovite and kaolinite minerals, which was supported from mineralogical point of view by DTA-TG analysis’s results as well. In the first part of the experimental study, both as-received and 270 min. attrition milled microgranite samples were added into the glazed porcelain body in the following proportions 8%, 12%, 16%, 20% meanwhile albite was removed from the standard body formulation. Following the wet ball milling of standard body and studied porcelain bodies, some test samples were prepared according to standard test procedure. The prepared samples were then taken to fast firing process in roller kilns under industrial conditions of 1200 ºC and 49 min. Prior to firing process slip properties of density (g/l), flow rate (s) and sieve residue (+63μ) were measured. Following this, the properties of fired body samples such as bulk density, shrinkage (%), water absorption (%), dry and fired strength and colour measurements expressed as L, a and b were measured as well. When compared with standard body, the results showed that the increase in microgranite amount decreased the water absorption and increased shrinkage and fired strength. Non-contact dilatometric analysis, Differential thermal analysis- thermogravimetric analysis (DTA-TGA) and X-ray diffraction (XRD) analysis were performed to determine the thermal expansion behaviours of the bodies, thermal behaviours of the bodies and the phases, respectively. Scanning electron microscope (SEM) in combination with energy dispersive X-ray spectroscopy (EDS) was further employed to observe the microstructure of the fired microgranite samples with respect to firing temperature. Moreover after firing process under industrial conditions quartz, plagioclase and mullite phases were detected in the bodies as the main phases. These observations were supported by DTA-TGA analyses as well. The inspection result of SEM image of the etched microgranite samples revealed that the sharp corners of the quartz grains were rounded by surface tension forces and the start of their partial solution into the glassy matrix has been observed. Based on these analyses and observations made during this study, it has been concluded that very fine grained microgranite material can be used in glazed porcelain tile bodies as a very good fluxing agent which leads to the suggestion that the removal of albite taken from Çine-Aydın region from the body recipe can be taken into consideration.

Özet

Seramik karolar, içinde yaşadığımız konutlarda yer ve duvar yüzeylerinde kaplama malzemesi olarak kullanılan inorganik malzeme içerikli ürünlerdir. Seramik karolar gelişen teknoloji ile sırlısırsız, duvar-yer-granit (porselen), iç-dış mekan olmak üzere çeşitli sınıflarda üretilmektedir. Bu çalışmada Bilecik-Karaköy civarındaki mikrogranitin atritör değirmende farklı sürelerde öğütülmüş halinin sırlı porselen bünyelere katılarak kullanım olanakları araştırılmıştır. Bilindiği üzere mikrogranitler ana olarak alkali feldspat, plajioklas ve kuvars minerallerinden oluşmaktadır. Holokristalen dokuda, orta kaba taneli, açık bej, gri ve beyaz renk tonlarında bulunabilen derinlik kayalarıdırlar. İlk olarak mikrogranit hammaddesi laboratuar tipi jet değirmende 20 dak. öğütülmüş, daha sonra bu çamur laboratuar tipi atritör değirmende 270 dak. öğütülerek etüvde kurutularak toz haline getirilmiştir. 270 dak. öğütülerek hazırlanmış malzeme standart sırlı granit porselen bünye içerisine %8, %12, %16 ve %20 katılarak bünyelerin endüstriyel rulolu fırınlarda 1200ºC-49 dak. pişirimleri yapılmıştır. Pişirim sonrası bünyelerin, bulk yoğunluk, pişme küçülmesi (%), su emme (%), pişmiş mukavemet (N/mm2) ve Renk L, a ve b değerleri belirlenmiş standart bünye ile mukayeseleri yapılmıştır. Bünyelerin termal davranışları DTA-TG (Diferansiyel Termal Analiz- Termogravimetri) analizi, Faz analizleri ise XRD (X-ray Difraktometre) ile belirlenmiştir. Tüm bünyelerin mikroyapısal incelemeleri SEM (Taramalı Elektron Mikroskobu) ile yapılmıştır. Sonuç olarak çok ince öğütülerek bünyelerde kullanılan mikrogranit malzemesinin çok iyi bir ergitici malzeme olduğu ve bünye içerisinde kullanılan diğer ergitici malzemelerin oranını %60’lara yakın azalttığı ortaya çıkmıştır.