Termo-Vakum İşlem Verimliliğini Tahmin Etmek İçin Bazı Sertlik Yöntemlerinin Karşılaştırılması

Öz

Durometre sertliği (Shore D), genellikle termoplastik elastomerler, vulkanize kauçuklar ve bazı plastiklerin sertliğini ölçmek için kullanılmaktadır. Bu çalışmada ise Shore D sertlik ölçüm yönteminin, ahşap sertliğinin belirlen-mesinde uygulanabilirliği araştırılmıştır. Ayrıca termo-vakum işlem görmüş malzemede elde edilen değerlerin, işlem görmemiş malzemeye göre farklı olup olmadığı da incelenmiştir. Çünkü yöntem, nispeten daha küçük olan ölçüm iğnesi ile bir tahribatsız değerlendirme yöntemi olarak yerinde ölçüm yapma potansiyeline sahiptir. Bu çalışmada, işlem görmemiş (kontrol) ve 200^oC'de termo-vakum (Termovuoto®) işlemine tabi tutulmuş sarıçam (Pinus sylvestris) örnekleri kullanılmıştır. İğne boyutu, yöntem prensibi ve yıllık halka yapısının getirdiği heterojenlik nedeniyle, tam radyal ve radyal numuneler hazırlanmış ve her grupta ilkbahar ve yaz odunu sertlikleri ölçülmüştür. Ayrıca verimliliği değerlendirmek amacıyla Shore D sertlik yöntemi, statik Janka sertlik yöntemiyle de karşılaştırılmıştır. Sonuçlar, anatomik özellikler dikkate alınarak durometre sertlik ölçüm cihazı ile ısıl işlem görme durumunun tahmin edilebileceğini göstermiştir. Kesiş yöntemi açısından, tam radyal ve radyal kesilmiş numunelerde elde edilen veriler benzer çıkmıştır. Yıllık halkalar esas alındığında; ilkbahar ve yaz odununda farklı sonuçlar elde edilmiştir. Ayrıca yaz odunu tabakası hem işlem görmemiş hem de işlem görmüş hem tam radyal ve hem de radyal kesilmiş numunelerde daha yüksek sonuçlar elde edilmiştir. Literatür incelendiğinde ise sarıçamda Shore D yöntemiyle elde edilen sonuçların geniş varyasyonda olduğu, bu çalışmadaki sonuçlarla anatomik farklılıkların dikkate alınmasıyla varyasyonun azalabileceği tespit edilmiştir. Diğer yandan Shore D yöntemiyle ilgili standartlarda diğer malzemelerin sertlik ölçümlerinde belirli ağırlıklar önerilmesine karşın, bu çalışmada testler insan kuvvetiyle heterojen bir şekilde gerçekleştirilse de düşük varyasyonlar elde edilmiştir. 

Anahtar Kelimeler

• Durometre
• janka
• sarıçam
• shore D
• termal modifikasyon

Comparing Some Hardness Methods for Estimating Thermo-Vacuum Treatment Efficiency

Öz

Durometer hardness (Shore D) is generally used for measuring hardness of the thermoplastic elastomers, vulcanized rubber, some plastics etc. In this study, availability of the Shore D hardness method for wood hardness was investigated. In addition, it was investigated whether the values ​​obtained from thermo-vacuum treated material differed from those obtained from untreated material. Because the method has potential for in-situ measurements as a non-destructive evaluation method with its relatively smaller measurement needle. Untreated and thermo-vacuum (Termovuoto®) treated at 200^oC treated Scots pine (Pinus sylvestris) samples were used in this study. Due to the needle size, method principle, and heterogeneity caused by annual ring structure, full radial and radial specimens were prepared, and earlywood and latewood hardness values were measured in each group. In addition, the Shore D hardness method was compared with the static Janka hardness method to evaluate efficiency. The results showed that the thermal treatment can be predicted using a durometer hardness tester with taking anatomical features into account. In terms of cutting method, the data obtained from fully radial and radially cut samples were similar. Based on annual rings, different results were obtained in early- and latewood. Furthermore, higher results were obtained in both untreated and treated latewood layers, and in both fully radial and radially cut samples. However, a review of the literature reveals that the results obtained using the Shore D method in Scots pine show significant variations. In light of the results of this study, it is suggested that anatomical differences should also be taken into account in order to eliminate variation dependent on macroscopic variables. Otherwise, although the standards related to the Shore D method recommend the application of standard weights in hardness measurements of other materials, in this study, low variations were obtained even though the tests were performed heterogeneously using human force.

Anahtar Kelimeler

• Durometer
• janka
• scots pine
• shore D
• thermal modification

Kaynakça

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